{
  "data": {
    "a": {
      "slug": "fone-me",
      "name": "fone.me",
      "vendor": "Fone",
      "vendorUrl": "https://www.fone.me",
      "kind": "platform",
      "category": "voice-agents",
      "summary": "fone.me is a hosted AI agent at a personal link that answers calls and messages for a person or small business over web chat, voice, WhatsApp, Telegram and a Premium number. Other agents reach it through keyless MCP and A2A.",
      "url": "https://www.anchorterminal.com/tools/fone-me",
      "markdownUrl": "https://www.anchorterminal.com/tools/fone-me.md",
      "slimMarkdownUrl": "https://www.anchorterminal.com/tools/fone-me.min.md",
      "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/fone-me.json",
      "dns": "fone-me.grade.anchorterminal.com",
      "license": "Proprietary hosted service. Terms of service at https://www.fone.me/terms, whose text draws by script and could not be read on 5 November 2026; no company is named on any page read. No source, SDK or package is published",
      "transports": [
        "streamable-http"
      ],
      "remoteUrl": "https://www.fone.me/mcp",
      "packages": [],
      "auth": "none",
      "authNotes": "No credential for callers. llms.txt gives the MCP server at https://www.fone.me/mcp as Streamable HTTP with auth 'none', and the README of the GitHub repository spearisa/fone-me-mcp says 'public, like the links themselves'. The A2A agent cards read (demo and maxr) declare no securitySchemes or security. The search API at /api/agents/search takes a query with no key per llms.txt. Owners sign in with Apple, Google or email to set up an agent; no owner API key, scopes or tokens are documented.",
      "pricing": "freemium",
      "pricingNotes": "The agent, the first link and the website chat button are free. Premium is $9.99 a month (llms.txt and https://www.fone.me/alternatives/smith-ai) and adds the agent's own phone number, calling minutes and more links, with cancellation at any time; no page read gives the minute allowance, the number of links, the countries for numbers or the payment method. Outbound calls use Premium minutes and international calls use more minutes per minute. Callers and outside agents pay nothing (checked 2026-11-05).",
      "priceSummary": "$9.99 / mo",
      "where": "hosted",
      "x402": {
        "level": "no",
        "evidence": "No x402, MPP or L402 in llms.txt, the guide pages read, the MCP repository README and server.json, or the two agent cards (checked 2026-11-05). The MCP server and A2A endpoints are free and keyless; Premium is a monthly subscription with no payment route stated.",
        "endpoints": []
      },
      "toolCount": 4,
      "popularity": {
        "githubStars": null,
        "npmWeekly": null,
        "pypiWeekly": null,
        "asOf": "2026-11-05"
      },
      "docsUrl": "https://www.fone.me/llms.txt",
      "llmsTxt": "https://www.fone.me/llms.txt",
      "capabilities": [
        "voice.agent",
        "voice.telephony",
        "voice.calls",
        "messaging.whatsapp",
        "messaging.inbound"
      ],
      "tags": [
        "hosted",
        "official",
        "closed-source",
        "mcp",
        "remote-mcp",
        "no-auth",
        "keyless",
        "a2a",
        "llms-txt",
        "whatsapp",
        "telegram",
        "ios",
        "freemium",
        "free-tier",
        "no-status-page"
      ],
      "lastRelease": "2026-10-05",
      "graded": true,
      "anchor": {
        "graded": true,
        "score": 28.3,
        "grade": "F",
        "agentReady": false,
        "rank": 1429,
        "ranked": true,
        "rankOf": 1510,
        "categoryRank": 26,
        "methodology": "0.7",
        "run": "2026-10-01",
        "scores": {
          "ergonomics": 29,
          "maintenance": 23,
          "payments": 50,
          "reliability": 15,
          "schema": 31,
          "security": 30,
          "transparency": 23
        },
        "pending": [
          "performance",
          "tasks"
        ],
        "assessment": {
          "confidence": "low",
          "date": "2026-11-05"
        },
        "negative": 0,
        "verdict": "Any agent can find a fone.me link and message its owner's agent through a keyless MCP server or A2A, with no sign-up or cost, and owners see every conversation in one inbox. Tool schemas, rate limits and abuse controls for that open channel are unpublished, the terms and privacy policy draw by script, and no company is named.",
        "bestFor": "Agents acting for a person who need to reach a freelancer's, shop's or small business's own AI agent at its fone.me link to ask a question, request a booking or quote or leave a message, and owners who want an answering agent on a link, WhatsApp, Telegram and a $9.99 number without building one.",
        "strengths": [
          "Keyless MCP server and per-link A2A endpoints let any agent find, look up and message a person's or business's agent without an account or payment",
          "Agent cards follow A2A 0.3.0 with skills, input and output modes and a JSON-RPC transport, readable at an address robots.txt allows",
          "Outbound calls disclose the agent and transcription, run only 8 am to 9 pm in the callee's time zone and stop permanently on a do-not-call request",
          "Owners see every call and chat with a transcript in one inbox, can take over at any time and approve what the agent will say before it calls",
          "Free agent, first link and website chat button, with Premium at $9.99 a month for a number and calling minutes"
        ],
        "weaknesses": [
          "No tool arguments, input schemas, annotations, error shapes or rate limits are published for the MCP server or A2A endpoints",
          "message_agent and A2A reach any person's agent with no caller identity, and no spam, rate or abuse control for that channel is documented",
          "The terms, privacy policy, data-deletion page, FAQ and support page draw by script, and no company, address or country of incorporation is named on any page read",
          "No status page, changelog, security.txt, SLA or published minute allowance for Premium",
          "robots.txt disallows the /mcp, /api/ and /*/a2a paths that llms.txt advertises to agents"
        ],
        "agentNotes": [
          "Connect to https://www.fone.me/mcp with no credentials; use find_agents or get_agent before message_agent so the message goes to the right person's link.",
          "Say who you are acting for in every message_agent call; the owner reads it in an inbox as a named conversation, and conversations continue across calls.",
          "Treat replies as the owner's agent speaking from what it was taught, not a commitment; the vendor says it asks its owner before agreeing to anything or spending money.",
          "Read a link's agent card at /{link}/.well-known/agent-card.json for its skills before using A2A message/send at /{link}/a2a.",
          "Don't send personal or payment details through message_agent; no retention or privacy terms for agent-to-agent messages could be read."
        ],
        "metrics": {
          "kind": "remote",
          "measured": false
        },
        "reviewCount": 0,
        "avgRating": 0,
        "history": [
          {
            "basis": "public evidence",
            "confidence": "low",
            "grade": "F",
            "methodology": "0.7",
            "pending": [
              "performance",
              "tasks"
            ],
            "run": "2026-10-01",
            "runLabel": "October 2026 research run",
            "score": 28.3
          }
        ],
        "editorialScores": {
          "ergonomics": 29,
          "maintenance": 23,
          "payments": 50,
          "reliability": 15,
          "schema": 31,
          "security": 30,
          "transparency": 13
        },
        "provenanceScore": 32,
        "checked": {
          "categories": {
            "ergonomics": "2026-11-05",
            "maintenance": "2026-11-05",
            "payments": "2026-11-05",
            "reliability": "2026-11-05",
            "schema": "2026-11-05",
            "security": "2026-11-05",
            "transparency": "2026-11-05"
          },
          "last": "2026-11-05",
          "oldest": "2026-11-05",
          "stale": false,
          "staleAfterDays": 90
        }
      },
      "connect": {
        "config": {
          "mcpServers": {
            "fone.me": {
              "type": "http",
              "url": "https://www.fone.me/mcp"
            }
          }
        }
      },
      "letme": {
        "capability": "https://letme.dev/voice.agent",
        "tool": "https://letme.dev/fone-me"
      },
      "area": "voice",
      "unitPrices": [
        {
          "item": "Premium",
          "unit": "month",
          "usd": 9.99,
          "note": "own fone.me number, calling minutes (allowance not published) and more links; the agent, first link and chat button are free"
        }
      ],
      "provenance": {
        "legalEntity": "",
        "domain": "fone.me",
        "domainRegistered": "",
        "endpointOnVendorDomain": true,
        "terms": "https://www.fone.me/terms",
        "privacy": "https://www.fone.me/privacy",
        "statusPage": "",
        "changelog": "",
        "securityTxt": "none",
        "checked": "2026-11-05",
        "notes": [
          "No legal entity is named on any page read. Page metadata gives the author and site name as 'Fone', and llms.txt gives San Francisco, CA, USA as a location. The terms, privacy policy and data-deletion page draw their text by script and showed only titles, so whether they name a company is unchecked, not absent.",
          "The README of github.com/spearisa/fone-me-mcp ends 'Operated by zwilio'. No fone.me page read names zwilio or links the repository, and three web searches found no company of that name, so it is not recorded as the legal entity.",
          "The MCP server, the search API and the A2A endpoints are on www.fone.me, the vendor's own domain. robots.txt disallows /mcp, /api/ and /*/a2a, so none was fetched; the agent cards it allows were read for two links.",
          "No status page or changelog found. /.well-known/security.txt answers with the app's HTML shell, recorded as none. /status failed to load.",
          "RDAP for fone.me, the Wayback Machine, the official MCP registry and the App Store listing (id 6759304762) were not read; each fetch needed an approval that did not come. firstReleased 2025-11-05 is the earliest sitemap lastmod (/sha_krux), a lower bound only, and falls one year to the day before the check, so the sitemap may cap its dates."
        ],
        "score": 32
      },
      "pageJsonUrl": "https://www.anchorterminal.com/tools/fone-me.json",
      "live": {
        "slug": "fone-me",
        "probe": {
          "target": "https://www.fone.me/mcp",
          "method": "get",
          "lastAt": "2026-11-07T19:22:07.71997153Z",
          "lastOk": true,
          "lastStatus": 405,
          "lastMs": 357,
          "authRequired": false,
          "uptime24h": 100,
          "uptime30d": 100,
          "p50ms24h": 215,
          "p95ms24h": 511,
          "samples24h": 210,
          "samples30d": 210,
          "days": [
            {
              "date": "2026-11-06",
              "probes": 13,
              "ok": 13
            },
            {
              "date": "2026-11-07",
              "probes": 197,
              "ok": 197
            }
          ]
        },
        "securityTxt": {
          "url": "https://fone.me/.well-known/security.txt",
          "state": "none",
          "checkedAt": "2026-11-07T15:59:59.997697627Z"
        },
        "llmsTxt": {
          "url": "https://www.fone.me/llms.txt",
          "ok": true,
          "status": 200,
          "checkedAt": "2026-11-07T15:32:32.136376991Z"
        },
        "pages": [
          {
            "url": "https://www.fone.me/privacy",
            "kind": "privacy",
            "status": 200,
            "checkedAt": "2026-11-07T14:28:42.001987885Z",
            "changedAt": "0001-01-01T00:00:00Z",
            "fingerprint": "e3b0c44298fc"
          },
          {
            "url": "https://www.fone.me/terms",
            "kind": "terms",
            "status": 200,
            "checkedAt": "2026-11-07T14:28:44.174787172Z",
            "changedAt": "0001-01-01T00:00:00Z",
            "fingerprint": "e3b0c44298fc"
          }
        ],
        "mcpTools": {
          "url": "https://www.fone.me/mcp",
          "checkedAt": "2026-11-07T01:44:39.315960369Z",
          "status": "ok",
          "note": "answered without the initialize handshake",
          "tools": [
            {
              "name": "find_agents",
              "title": "Find people and businesses on fone.me",
              "description": "Search fone.me for people's and businesses' AI agents by what they do or offer (e.g. 'dog walker', 'real estate agent in Miami', 'Spanish tutor'). Returns their fone.me links.",
              "inputSchema": {
                "properties": {
                  "limit": {
                    "description": "How many results (1-10). Default 5.",
                    "type": "number"
                  },
                  "query": {
                    "description": "What you're looking for, in plain words.",
                    "type": "string"
                  }
                },
                "required": [
                  "query"
                ],
                "type": "object"
              },
              "annotations": {
                "openWorldHint": true,
                "readOnlyHint": true,
                "title": "Find people and businesses on fone.me"
              }
            },
            {
              "name": "get_agent",
              "title": "Look up a fone.me agent",
              "description": "Get who is behind a fone.me link (e.g. fone.me/samspearin) and what their agent can help with, before messaging it.",
              "inputSchema": {
                "properties": {
                  "link": {
                    "description": "A fone.me link or name, e.g. 'fone.me/sam' or 'sam'.",
                    "type": "string"
                  }
                },
                "required": [
                  "link"
                ],
                "type": "object"
              },
              "annotations": {
                "openWorldHint": true,
                "readOnlyHint": true,
                "title": "Look up a fone.me agent"
              }
            },
            {
              "name": "message_agent",
              "title": "Message a fone.me agent",
              "description": "Send a message to the AI agent at a fone.me link and get its reply — ask a question, request a booking or a quote, or leave a message for the person. The conversation continues across calls. Say who you're asking for in on_behalf_of.",
              "inputSchema": {
                "properties": {
                  "link": {
                    "description": "A fone.me link or name, e.g. 'fone.me/samspearin'.",
                    "type": "string"
                  },
                  "message": {
                    "description": "What to say to the agent.",
                    "type": "string"
                  },
                  "on_behalf_of": {
                    "description": "The name of the person you're asking for (shown to the owner).",
                    "type": "string"
                  }
                },
                "required": [
                  "link",
                  "message"
                ],
                "type": "object"
              },
              "annotations": {
                "destructiveHint": false,
                "idempotentHint": false,
                "openWorldHint": true,
                "readOnlyHint": false,
                "title": "Message a fone.me agent"
              }
            },
            {
              "name": "add_chat_to_website",
              "title": "Add an AI chat button to a website",
              "description": "Get the one-line code that puts a fone.me AI agent on a website: a chat button in the corner where visitors chat, call by voice, or continue on WhatsApp or Telegram, and the agent answers questions, takes messages and booking requests for the owner. Use it when someone building or editing a website (HTML, Next.js, React, WordPress, Shopify, Wix, Squarespace, Webflow, Framer) wants a chatbot, AI receptionist, live chat or contact widget. Free to start. Give the person's fone.me link if they have one.",
              "inputSchema": {
                "properties": {
                  "link": {
                    "description": "The site owner's fone.me link, e.g. 'fone.me/joes-plumbing' or 'joes-plumbing'. Leave out if they don't have one yet.",
                    "type": "string"
                  },
                  "site": {
                    "description": "What the site is built with: html, nextjs, react, wordpress, shopify, wix, squarespace, webflow, framer. Default html.",
                    "type": "string"
                  }
                },
                "type": "object"
              },
              "annotations": {
                "openWorldHint": true,
                "readOnlyHint": true,
                "title": "Add an AI chat button to a website"
              }
            }
          ],
          "schemaTokens": 725,
          "changedAt": "2026-11-07T01:44:39.315960369Z",
          "check": {
            "checker": "anchor-check/1.0",
            "totalTokens": 725,
            "counts": {
              "error": 0,
              "note": 1,
              "warn": 1
            },
            "findings": [
              {
                "rule": "TC18",
                "severity": "warn",
                "tool": "add_chat_to_website",
                "message": "readOnlyHint is true but the name says \"add\"",
                "fix": "If it changes anything, readOnlyHint must be false."
              },
              {
                "rule": "TC24",
                "severity": "note",
                "message": "4 of 4 tools have no outputSchema",
                "fix": "Declare outputSchema for tools that return structured data, and return structuredContent that matches it."
              }
            ]
          }
        },
        "updatedAt": "2026-11-07T19:22:07.71997153Z"
      }
    },
    "answer": "Ultravox Realtime API scores 59.2 (C) on agent readiness against fone.me's 28.3 (F), and leads in 6 of 7 scored categories. fone.me leads on payments \u0026 pricing.",
    "b": {
      "slug": "ultravox",
      "name": "Ultravox Realtime API",
      "vendor": "Ultravox (Fixie.ai)",
      "vendorUrl": "https://www.ultravox.ai",
      "kind": "http-api",
      "category": "voice-agents",
      "summary": "Hosted voice agents on Ultravox, an open-weight model that takes speech directly with no speech-to-text step and answers through a TTS voice.",
      "url": "https://www.anchorterminal.com/tools/ultravox",
      "markdownUrl": "https://www.anchorterminal.com/tools/ultravox.md",
      "slimMarkdownUrl": "https://www.anchorterminal.com/tools/ultravox.min.md",
      "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/ultravox.json",
      "dns": "ultravox.grade.anchorterminal.com",
      "repo": "https://github.com/fixie-ai/ultravox",
      "license": "MIT (model code)",
      "transports": [
        "http"
      ],
      "remoteUrl": "https://api.ultravox.ai/api",
      "packages": [
        {
          "registry": "npm",
          "name": "ultravox-client"
        },
        {
          "registry": "pypi",
          "name": "ultravox-client"
        }
      ],
      "auth": "api-key",
      "authNotes": "`X-API-Key` header on the REST API. Clients join a call with the `joinUrl` returned when it's created, so the key stays on your server.",
      "pricing": "usage",
      "pricingNotes": "Pay as you go at $0.05 a minute after 30 free minutes, capped at 5 concurrent calls. Pro is $100 a month (annual rate) at the same $0.05 a minute with no hard concurrency cap, the outbound scheduler, 5 custom voices and 20 RAG corpora. SIP costs 0.5 cents a minute (0.48 on Pro). Threads are $2 per 1M input tokens and $15 per 1M output. Enterprise is custom. Telephony from Twilio or other carriers is billed by them (https://www.ultravox.ai/pricing).",
      "priceSummary": "$100 / mo",
      "where": "hosted",
      "x402": {
        "level": "no",
        "evidence": "No x402 support in the docs, pricing page or MCP docs (checked 2026-09-30).",
        "endpoints": []
      },
      "toolCount": null,
      "popularity": {
        "githubStars": 4574,
        "npmWeekly": 17262,
        "pypiWeekly": null,
        "asOf": "2026-09-30"
      },
      "docsUrl": "https://docs.ultravox.ai",
      "llmsTxt": "https://docs.ultravox.ai/llms.txt",
      "openapi": "https://api.ultravox.ai/api/schema/",
      "capabilities": [
        "voice.agent",
        "voice.speech-to-speech",
        "voice.tools",
        "voice.telephony"
      ],
      "tags": [
        "hosted",
        "open-weights",
        "no-card",
        "llms-txt",
        "openapi",
        "typescript",
        "python",
        "webhooks",
        "streaming",
        "speech-to-speech"
      ],
      "lastRelease": "2026-07-18",
      "graded": true,
      "anchor": {
        "graded": true,
        "score": 59.2,
        "grade": "C",
        "agentReady": false,
        "rank": 715,
        "ranked": true,
        "rankOf": 1510,
        "categoryRank": 14,
        "methodology": "0.7",
        "run": "2026-10-01",
        "scores": {
          "ergonomics": 69,
          "maintenance": 53,
          "payments": 40,
          "reliability": 52,
          "schema": 84,
          "security": 46,
          "transparency": 71
        },
        "pending": [
          "performance",
          "tasks"
        ],
        "assessment": {
          "confidence": "medium",
          "date": "2026-11-04"
        },
        "negative": 0,
        "verdict": "Flat $0.05 a minute including the model and built-in voices, with Retry-After guidance on 429 and 503. Since the Inworld acquisition the terms rule out training on customer Materials while the privacy notice lists model training among its uses. No MCP server, and the status page refuses automated readers.",
        "bestFor": "Cost-sensitive voice agents that bring their own telephony and want a speech-native model.",
        "strengths": [
          "Flat $0.05 a minute including model and built-in voices",
          "Speech-native model with no separate STT stage, v0.7 weights public under MIT",
          "429 and 503 responses with Retry-After and backoff guidance",
          "Deprecation guide with a minimum 30-day window and dated entries, the newest on 3 November 2026",
          "API keys can be created, given an expiry and revoked through the API"
        ],
        "weaknesses": [
          "No MCP server",
          "Inworld's privacy notice lists training its AI models among the uses of collected content, while the terms say customer Materials aren't used for training",
          "News page and Python client last updated in December 2025, and no client release since July 2026",
          "Plain API keys with no scopes",
          "No subprocessor list, security.txt or readable certification"
        ],
        "agentNotes": [
          "Honour `Retry-After` on 429 and 503 when creating calls",
          "Pin the model string (`ultravox-v0.7` or `ultravox-v0.6`) rather than relying on the default",
          "Hand clients the `joinUrl`, never the API key",
          "When continuing a call with `priorCallId`, send the full call configuration in the body; fields stop being inherited by 7 December 2026",
          "Delete calls through the API when you need data removed, there's no retention setting"
        ],
        "metrics": {
          "kind": "remote",
          "measured": false
        },
        "reviewCount": 2,
        "avgRating": 3,
        "history": [
          {
            "basis": "public evidence",
            "confidence": "medium",
            "grade": "C",
            "methodology": "0.7",
            "pending": [
              "performance",
              "tasks"
            ],
            "run": "2026-10-01",
            "runLabel": "October 2026 research run",
            "score": 59.2
          }
        ],
        "editorialScores": {
          "ergonomics": 69,
          "maintenance": 53,
          "payments": 40,
          "reliability": 52,
          "schema": 84,
          "security": 46,
          "transparency": 62
        },
        "provenanceScore": 80,
        "checked": {
          "categories": {
            "ergonomics": "2026-11-04",
            "maintenance": "2026-11-04",
            "payments": "2026-11-04",
            "reliability": "2026-11-04",
            "schema": "2026-11-04",
            "security": "2026-11-04",
            "transparency": "2026-11-04"
          },
          "last": "2026-11-04",
          "lastMoved": "2026-11-04",
          "oldest": "2026-11-04",
          "stale": false,
          "staleAfterDays": 90
        }
      },
      "connect": {
        "http": "curl -X POST https://api.ultravox.ai/api/calls -H \"X-API-Key: $ULTRAVOX_API_KEY\" \\\n  -H \"content-type: application/json\" \\\n  -d '{\"systemPrompt\":\"You are a friendly receptionist.\",\"voice\":\"Mark\"}'"
      },
      "letme": {
        "capability": "https://letme.dev/voice.agent",
        "tool": "https://letme.dev/ultravox"
      },
      "sameCompany": [
        "ultravox-voice-cloning"
      ],
      "area": "voice",
      "unitPrices": [
        {
          "item": "Ultravox Realtime",
          "unit": "call-minute",
          "usd": 0.05,
          "note": "model and built-in voices, telephony carrier costs extra"
        },
        {
          "item": "SIP",
          "unit": "call-minute",
          "usd": 0.005,
          "note": "0.0048 on Pro"
        },
        {
          "item": "Pro plan",
          "unit": "month",
          "usd": 100,
          "note": "annual rate"
        }
      ],
      "provenance": {
        "legalEntity": "Theai, Inc. dba Inworld AI",
        "domain": "ultravox.ai",
        "domainRegistered": "2023-10-05",
        "endpointOnVendorDomain": true,
        "terms": "https://www.ultravox.ai/terms",
        "privacy": "https://www.ultravox.ai/privacy",
        "statusPage": "https://status.ultravox.ai",
        "changelog": "https://docs.ultravox.ai/changelog/news",
        "securityTxt": "none",
        "checked": "2026-11-04",
        "notes": [
          "The terms of service at www.ultravox.ai/terms are Inworld AI's, effective 1 October 2026, and name Theai, Inc. dba Inworld AI; the earlier terms, which named Fixie.ai Inc., are at ultravox.ai/terms-old. A site banner says Ultravox has been acquired by Inworld.",
          "The privacy notice at www.ultravox.ai/privacy is the Inworld AI Privacy Notice, effective 1 October 2026.",
          "status.ultravox.ai's robots.txt disallows every path for every agent, re-read on 2026-11-04.",
          "www.ultravox.ai/.well-known/security.txt answers 404. inworld.ai's robots.txt carries `Content-Signal: ai-train=no, search=yes, ai-input=no`."
        ],
        "score": 80
      },
      "pageJsonUrl": "https://www.anchorterminal.com/tools/ultravox.json",
      "live": {
        "slug": "ultravox",
        "probe": {
          "target": "https://api.ultravox.ai/api",
          "method": "get",
          "lastAt": "2026-11-07T19:22:42.078700316Z",
          "lastOk": true,
          "lastStatus": 404,
          "lastMs": 166,
          "authRequired": false,
          "uptime24h": 100,
          "uptime30d": 100,
          "p50ms24h": 142,
          "p95ms24h": 253,
          "samples24h": 238,
          "samples30d": 7920,
          "days": [
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              "date": "2026-10-07",
              "probes": 272,
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            },
            {
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              "probes": 268,
              "ok": 268
            },
            {
              "date": "2026-10-09",
              "probes": 250,
              "ok": 250
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              "date": "2026-10-10",
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            {
              "date": "2026-10-15",
              "probes": 253,
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            {
              "date": "2026-10-16",
              "probes": 252,
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            {
              "date": "2026-10-17",
              "probes": 253,
              "ok": 253
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            {
              "date": "2026-10-18",
              "probes": 256,
              "ok": 256
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            {
              "date": "2026-10-19",
              "probes": 255,
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            {
              "date": "2026-10-20",
              "probes": 252,
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            {
              "date": "2026-10-21",
              "probes": 253,
              "ok": 253
            },
            {
              "date": "2026-10-22",
              "probes": 253,
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            {
              "date": "2026-10-23",
              "probes": 248,
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              "date": "2026-10-24",
              "probes": 251,
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              "date": "2026-10-25",
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            {
              "date": "2026-10-26",
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            },
            {
              "date": "2026-10-27",
              "probes": 249,
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            },
            {
              "date": "2026-10-28",
              "probes": 250,
              "ok": 250
            },
            {
              "date": "2026-10-29",
              "probes": 249,
              "ok": 249
            },
            {
              "date": "2026-10-30",
              "probes": 249,
              "ok": 249
            },
            {
              "date": "2026-10-31",
              "probes": 251,
              "ok": 251
            },
            {
              "date": "2026-11-01",
              "probes": 249,
              "ok": 249
            },
            {
              "date": "2026-11-02",
              "probes": 250,
              "ok": 250
            },
            {
              "date": "2026-11-03",
              "probes": 248,
              "ok": 248
            },
            {
              "date": "2026-11-04",
              "probes": 246,
              "ok": 246
            },
            {
              "date": "2026-11-05",
              "probes": 185,
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            {
              "date": "2026-11-06",
              "probes": 241,
              "ok": 241
            },
            {
              "date": "2026-11-07",
              "probes": 197,
              "ok": 197
            }
          ]
        },
        "vendorStatus": {
          "page": "https://status.ultravox.ai",
          "indicator": "unknown",
          "summary": "no machine-readable status found",
          "checkedAt": "2026-11-06T23:09:07.754460187Z"
        },
        "versions": [
          {
            "registry": "github",
            "name": "fixie-ai/ultravox",
            "version": "v0.6",
            "released": "2025-08-18",
            "seenAt": "2026-11-07T00:13:46.410504435Z"
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          {
            "registry": "npm",
            "name": "ultravox-client",
            "version": "0.6.0",
            "seenAt": "2026-11-07T00:13:44.335543797Z"
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          {
            "registry": "pypi",
            "name": "ultravox-client",
            "version": "0.1.0",
            "released": "2025-12-10",
            "seenAt": "2026-11-07T00:13:45.134579448Z"
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        ],
        "githubStars": 4585,
        "npmWeekly": 16984,
        "pypiWeekly": 174,
        "securityTxt": {
          "url": "https://ultravox.ai/.well-known/security.txt",
          "state": "none",
          "checkedAt": "2026-11-07T16:00:53.508581161Z"
        },
        "llmsTxt": {
          "url": "https://docs.ultravox.ai/llms.txt",
          "ok": true,
          "status": 200,
          "checkedAt": "2026-11-07T15:34:15.052985662Z"
        },
        "domain": {
          "domain": "ultravox.ai",
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          "source": "https://rdap.identitydigital.services/rdap/domain/ultravox.ai",
          "checkedAt": "2026-11-01T14:12:30.702624774Z"
        },
        "pages": [
          {
            "url": "https://docs.ultravox.ai/changelog/deprecation",
            "kind": "deprecations",
            "status": 200,
            "checkedAt": "2026-11-07T14:08:28.239062701Z",
            "changedAt": "0001-01-01T00:00:00Z",
            "fingerprint": "5d02e17c1eba"
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        "github": {
          "repo": "fixie-ai/ultravox",
          "checkedAt": "2026-11-02T08:48:52.314300024Z",
          "stars": 4583,
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          "issuesEnabled": true,
          "pushedAt": "2025-12-12T18:09:40Z",
          "openIssues": 53,
          "openPRs": 9,
          "issuesOpened90d": 0,
          "issuesClosed90d": 1,
          "prsMerged90d": 0,
          "ci": {
            "branch": "main",
            "runs": 1,
            "success": 1,
            "failure": 0,
            "other": 0,
            "latest": "success",
            "latestAt": "2025-12-12T18:14:55Z"
          },
          "replies": {
            "sampled": 25,
            "unanswered": 17,
            "medianDays": 25
          }
        },
        "updatedAt": "2026-11-07T19:22:42.078700316Z"
      }
    },
    "edges": [
      {
        "by": 53,
        "category": "schema",
        "leads": "ultravox",
        "name": "Schema \u0026 documentation",
        "reasons": {
          "a": "MCP reading, since the MCP server is what an outside agent calls. No tool arguments or input schemas are published in llms.txt, the guide pages or the GitHub README, and robots.txt disallows /mcp, so no session was opened and tools/list was not read. Per-link A2A agent cards are machine-readable JSON (protocol 0.3.0, JSONRPC, input and output modes, skills with examples) and server.json names the remote, but neither types the MCP tools (8 of 25). llms.txt is a real document for agents covering the MCP server, A2A, the search API and the widget (10). Each tool has a one-line purpose in llms.txt and the README, and the how-it-works page states what the agent will and won't do; nothing says when not to use a tool (6 of 20). No typed inputs, enums, constraints or required fields published (0 of 15). Example prompts in the README, per-skill examples in agent cards and widget code for eight site builders; no error response is documented (4 of 15). server.json and the agent cards carry version 1.0.0 and the cards a protocol version; no changelog (3 of 15). 8+10+6+0+4+3 = 31.",
          "b": "OpenAPI schema at api.ultravox.ai/api/schema/ (25). llms.txt with Markdown copies (10). Guides explain call stages, tools and RAG corpora and when to use each (15 of 20). The OpenAPI types call creation with enums and required fields (13 of 15). Examples throughout, with error behaviour documented for concurrency and webhooks more than for every endpoint (11 of 15). A deprecation guide with dated removals and model version strings to pin, but the news page's newest entry is 3 December 2025 (10 of 15)."
        },
        "scores": {
          "a": 31,
          "b": 84
        }
      },
      {
        "by": 48,
        "category": "transparency",
        "leads": "ultravox",
        "name": "Transparency \u0026 trust",
        "reasons": {
          "a": "Closed service. Terms of service exist at /terms but draw by script, so their content, governing law and the company they name are unchecked; no company, address or country of incorporation appears on any page read, llms.txt says San Francisco, and the MCP repository has no licence (5 of 30). Data handling was read only from guide pages, which say only the owner sees their calls and messages, calls are transcribed and callers told so, and private categories are withheld. The privacy policy and data-deletion page draw by script, so no retention period, recording statement, DPA or AI-training statement was read (8 of 30). No deprecation policy or dated notices (0). No subprocessors, telephony, model or hosting providers or data locations are named on any page read; the demo agent card's icon is served from Cloudinary (0 of 20). 5+8+0+0 = 13.",
          "b": "The Ultravox model code is MIT on GitHub, and the v0.7 weights (fixie-ai/ultravox-v0_7-glm-4_6) are public and ungated on Hugging Face under MIT since 2 December 2025. The hosted service is closed (26 of 30). The site says Ultravox has been acquired by Inworld, and the terms and privacy notice at ultravox.ai are now Inworld AI's, both effective 1 October 2026. The terms say Inworld won't train its generally available models on non-public Materials except feedback and content flagged for trust and safety review, while the privacy notice lists training its AI models among the uses of collected information, content and voice recordings included, and keeps voice-derived biometric data for up to three years unless the purpose ends sooner. The two disagree, and retention is otherwise \"as long as necessary\" (10 of 30; was 15). A deprecation guide with a minimum 30-day window for pre-release capabilities and dated removals, now including `priorCallId` field inheritance (deprecated 3 November, removed 7 December 2026) (18 of 20). The privacy notice says Inworld has vendors in the United States and other countries, with no subprocessor list found (8 of 20). 26 + 10 + 18 + 8 = 62."
        },
        "scores": {
          "a": 23,
          "b": 71
        }
      },
      {
        "by": 40,
        "category": "ergonomics",
        "leads": "ultravox",
        "name": "Agent ergonomics",
        "reasons": {
          "a": "MCP reading. Four tools named in llms.txt, a small set, but their definitions were not read, so short of full marks (18 of 25). find_agents searches by what someone does and the search API takes a query; no limit, paging or output-size controls are documented (3 of 20). No error codes or messages documented for the MCP server, the search API or A2A (0 of 20). No readOnlyHint or destructiveHint seen and no idempotency key; the three lookups are read-only by name and description, while message_agent writes to a real person's inbox and continues the conversation across calls (2 of 20). No credentials, no configuration beyond the URL, and few stated inputs; no SDK in any language (6 of 15). 18+3+0+2+6 = 29.",
          "b": "Scored as an API, since there's no MCP server. Calls and messages list with cursors and page sizes (18 of 25). Paging and filters on calls (17 of 20). 429 and 503 come with Retry-After, which an agent can act on (14 of 20). No idempotency keys on call creation (5 of 20). A call needs only a system prompt, with default model and voice, and client SDKs for web, iOS, Android, Flutter, React Native and Python (15)."
        },
        "scores": {
          "a": 29,
          "b": 69
        }
      },
      {
        "by": 37,
        "category": "reliability",
        "leads": "ultravox",
        "name": "Reliability",
        "reasons": {
          "a": "Hosted reading, for the MCP server and A2A endpoints and the service behind them. No status page is linked from llms.txt, the home page or any guide page read, and https://www.fone.me/status failed to load (0). No readable incident history, so the floor (5). No request rate limit for the MCP server, the search API or A2A is published; the only limits are on the agent's own outbound calls (8 am to 9 pm in the callee's time zone, 'limited per day' with no number), which are not request limits (0 of 15). No 429, overload or retry guidance and no idempotency key for message_agent or message/send (0 of 15). No SLA (0). Nothing on the MCP server, the agent cards or llms.txt is marked beta or preview, and the MCP repository's server.json is version 1.0.0 (10). 0+5+0+0+0+10 = 15.",
          "b": "A status page sits at status.ultravox.ai, but its robots.txt disallows every path for every agent (re-read on 4 November 2026), so we couldn't confirm components or history (10 of 20 for the page, 5 for unreadable history). Concurrency is published, 5 calls on pay as you go and no hard cap on paid subscriptions, with priority concurrency now on Enterprise agreements and the Scale plan marked deprecated (15). Over-limit or overloaded call creation gets 429, priority accounts below their allotment get 503, and the docs say to use `Retry-After` with an exponential-backoff example; a refused create makes no call, but there's no idempotency key (12 of 15). No SLA found; Enterprise lists a response SLA only (0). The Realtime API is generally available (10). 10 + 5 + 15 + 12 + 0 + 10 = 52."
        },
        "scores": {
          "a": 15,
          "b": 52
        }
      },
      {
        "by": 30,
        "category": "maintenance",
        "leads": "ultravox",
        "name": "Maintenance \u0026 community",
        "reasons": {
          "a": "Closed service. The newest dated change to the agent surface found is the MCP repository github.com/spearisa/fone-me-mcp, created 5 October 2026 with server.json version 1.0.0, 31 days ago (20). The comparison page marked 'Checked October 28, 2026' and the profile lastmods in the sitemap are content, not releases. No changelog, release notes or three dated changes in 90 days (0 of 20). The support page and FAQ draw by script and no support email, forum or community channel was found; responsiveness unchecked (3 of 15). server.json names the server me.fone.www/agents, a namespace that needs proof of the domain, but the official MCP registry could not be read, so presence is scored absent (0 of 15). No package, public code or CI (0 of 10). 20+0+3+0+0 = 23.",
          "b": "The deprecation guide added a dated entry on 3 November 2026 for `priorCallId` inheriting call fields, deprecated that day and removed on 7 December 2026, with a migration link to the making-calls guide. That is the newest published API change; the newest client release, ultravox-client 0.6.0 (tag 17 July, npm 18 July 2026), is 109 days old (30; was 20). Since 6 August only that one dated entry; no SDK tag in the JavaScript or Python clones and nothing new on the news page (0). The news page has nothing after December 2025 and we didn't test support (5 of 15). Client SDKs for six platforms. JavaScript 0.6.0 is the newest, the Python client's last release is 0.1.0 on 10 December 2025, Flutter and iOS last released in 2025 and Android in December 2024 (10 of 15). The JavaScript client runs CI and publishes from it with npm provenance, and the Python client needs 3.10 or later (8 of 10). 30 + 0 + 5 + 10 + 8 = 53."
        },
        "scores": {
          "a": 23,
          "b": 53
        }
      },
      {
        "by": 16,
        "category": "security",
        "leads": "ultravox",
        "name": "Security \u0026 auth",
        "reasons": {
          "a": "No credential exists for callers. llms.txt gives auth 'none', the README says the server is 'public, like the links themselves', and the two agent cards read declare no security scheme. There is nothing to leak or rotate, but fone.me and an owner can tell callers apart only by the name they give ('Maria via ChatGPT' in the README) and by traffic, and no caller identity or verification is documented (10 of 30). Three of four MCP tools are lookups; message_agent and A2A message/send reach any owner's agent. On the owner's side the vendor says the agent asks before agreeing to anything or spending money, the owner approves what it will say before a call, outbound calls run only 8 am to 9 pm local, pause when reported and stop permanently on request, and the owner can take over any chat. No read-only mode and no confirmation on the caller's side (8 of 20). message_agent returns text generated from what the owner taught the agent, and every agent on the platform reads messages from anyone; the only guidance is the how-it-works statement that the agent keeps relationship status, health, money and address private, with no documented prompt-injection or spam handling for the open channel, and the call-screening page says it does not promise to block calls (4 of 15). Owners see every call and chat with a transcript in one inbox; nothing is logged for the calling agent (8 of 15). /.well-known/security.txt answers with the app shell, and no disclosure policy, bug bounty or certification appears on any page read (0 of 20). 10+8+4+8+0 = 30.",
          "b": "Plain API keys in the `X-API-Key` header, which the OpenAPI document shows can be created, given an expiry, revoked and deleted through `/api/api_keys`, with no scopes; each call returns a `joinUrl` so clients never see the key (20). We found no scoped or read-only keys (8 of 20). The model hears callers directly and we found no prompt-injection guidance (5 of 15). Call records and a delete-call API, but no audit log (8 of 15). No security.txt (www.ultravox.ai answers 404). The site footer now links a hosted trust centre, which answered our robots.txt request with a Vercel bot check, so its contents are unchecked. Webhook signing is documented (5 of 20). 20 + 8 + 5 + 8 + 5 = 46."
        },
        "scores": {
          "a": 30,
          "b": 46
        }
      }
    ],
    "facts": [
      {
        "a": "Platform",
        "b": "HTTP API",
        "name": "Kind"
      },
      {
        "a": "Fone",
        "b": "Ultravox (Fixie.ai)",
        "name": "Vendor"
      },
      {
        "a": "https://www.fone.me/mcp",
        "b": "https://api.ultravox.ai/api",
        "name": "Hosted endpoint"
      },
      {
        "a": "Streamable HTTP",
        "b": "HTTP",
        "name": "Transports"
      },
      {
        "a": "None",
        "b": "API key",
        "name": "Auth"
      },
      {
        "a": "Freemium",
        "b": "Pay per use",
        "name": "Pricing"
      },
      {
        "a": "no",
        "b": "no",
        "name": "x402"
      },
      {
        "a": "Proprietary hosted service. Terms of service at https://www.fone.me/terms, whose text draws by script and could not be read on 5 November 2026; no company is named on any page read. No source, SDK or package is published",
        "b": "MIT (model code)",
        "name": "Licence"
      },
      {
        "a": "4",
        "b": "none",
        "name": "Tools exposed"
      },
      {
        "a": "no",
        "b": "no",
        "name": "Read-only variant documented"
      },
      {
        "a": "yes",
        "b": "yes",
        "name": "llms.txt"
      },
      {
        "a": "2026-10-05",
        "b": "2026-07-18",
        "name": "Last release"
      },
      {
        "a": "couldn't be read",
        "b": "2026-10-01",
        "name": "Terms last updated"
      },
      {
        "a": "couldn't be read",
        "b": "2026-10-01",
        "name": "Privacy policy last updated"
      },
      {
        "a": "couldn't be read",
        "b": "yes",
        "name": "Customer content may train models"
      },
      {
        "a": "couldn't be read",
        "b": "not found in the text",
        "name": "Terms restrict automated access"
      },
      {
        "a": "couldn't be read",
        "b": "not found in the text",
        "name": "Terms restrict benchmarking"
      },
      {
        "a": "couldn't be read",
        "b": "not found in the text",
        "name": "Terms or service can change without notice"
      },
      {
        "a": "couldn't be read",
        "b": "not found in the text",
        "name": "Arbitration or class-action waiver"
      },
      {
        "a": "none",
        "b": "4.6k stars, 17k npm/wk",
        "name": "Popularity"
      },
      {
        "a": "none",
        "b": "3/5 (2)",
        "name": "Agent reviews"
      }
    ],
    "faq": [
      {
        "answer": "Ultravox Realtime API scores 59.2 (C) on agent readiness against fone.me's 28.3 (F), and leads in 6 of 7 scored categories. fone.me leads on payments \u0026 pricing.",
        "question": "Which is better for AI agents, fone.me or Ultravox Realtime API?"
      },
      {
        "answer": "Yes. fone.me has a hosted endpoint at https://www.fone.me/mcp and Ultravox Realtime API at https://api.ultravox.ai/api.",
        "question": "Can an agent call fone.me and Ultravox Realtime API without installing anything?"
      }
    ],
    "goodFor": [
      {
        "aheadOn": [
          "Payments \u0026 pricing, 50 against 40"
        ],
        "also": [
          "No key needed to call it"
        ],
        "goodFor": "Agents acting for a person who need to reach a freelancer's, shop's or small business's own AI agent at its fone.me link to ask a question, request a booking or quote or leave a message, and owners who want an answering agent on a link, WhatsApp, Telegram and a $9.99 number without building one.",
        "slug": "fone-me",
        "watchFor": "No tool arguments, input schemas, annotations, error shapes or rate limits are published for the MCP server or A2A endpoints"
      },
      {
        "aheadOn": [
          "Reliability, 52 against 15",
          "Schema \u0026 documentation, 84 against 31",
          "Agent ergonomics, 69 against 29",
          "Security \u0026 auth, 46 against 30",
          "Maintenance \u0026 community, 53 against 23",
          "Transparency \u0026 trust, 71 against 23"
        ],
        "also": [
          "Free to start without a card"
        ],
        "goodFor": "Cost-sensitive voice agents that bring their own telephony and want a speech-native model.",
        "slug": "ultravox",
        "watchFor": "No MCP server"
      }
    ],
    "history": {
      "fone-me": null,
      "ultravox": [
        {
          "causes": [
            "terms",
            "product"
          ],
          "date": "2026-11-04",
          "delta": 0.6,
          "from": 58.6,
          "fromGrade": "C",
          "to": 59.2,
          "toGrade": "C"
        },
        {
          "causes": [
            "evidence"
          ],
          "date": "2026-10-29",
          "delta": 0.1,
          "from": 58.5,
          "fromGrade": "C",
          "to": 58.6,
          "toGrade": "C"
        },
        {
          "causes": [
            "method"
          ],
          "date": "2026-10-08",
          "delta": -0.1,
          "from": 58.6,
          "fromGrade": "C",
          "to": 58.5,
          "toGrade": "C"
        }
      ]
    },
    "job": {
      "capability": "voice.agent",
      "name": "Voice agents"
    },
    "others": [
      {
        "json": "https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-fone-me.json",
        "title": "Amazon Nova 2 Sonic vs fone.me",
        "url": "https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-fone-me"
      },
      {
        "json": "https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-ultravox.json",
        "title": "Amazon Nova 2 Sonic vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-fone-me.json",
        "title": "AssemblyAI Voice Agent API vs fone.me",
        "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-fone-me"
      },
      {
        "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-ultravox.json",
        "title": "AssemblyAI Voice Agent API vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/bland-ai-vs-fone-me.json",
        "title": "Bland AI API + MCP vs fone.me",
        "url": "https://www.anchorterminal.com/compare/bland-ai-vs-fone-me"
      },
      {
        "json": "https://www.anchorterminal.com/compare/bland-ai-vs-ultravox.json",
        "title": "Bland AI API + MCP vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/bland-ai-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/bolna-vs-fone-me.json",
        "title": "Bolna API + MCP vs fone.me",
        "url": "https://www.anchorterminal.com/compare/bolna-vs-fone-me"
      },
      {
        "json": "https://www.anchorterminal.com/compare/bolna-vs-ultravox.json",
        "title": "Bolna API + MCP vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/bolna-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-fone-me.json",
        "title": "Deepgram Voice Agent API vs fone.me",
        "url": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-fone-me"
      },
      {
        "json": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-ultravox.json",
        "title": "Deepgram Voice Agent API vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-fone-me.json",
        "title": "ElevenLabs Agents API + MCP vs fone.me",
        "url": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-fone-me"
      },
      {
        "json": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-ultravox.json",
        "title": "ElevenLabs Agents API + MCP vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-gemini-live.json",
        "title": "fone.me vs Gemini Live API",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-gemini-live"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-gpt-live.json",
        "title": "fone.me vs GPT-Live",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-gpt-live"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-harmony-ai.json",
        "title": "fone.me vs Harmony.ai",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-harmony-ai"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-hume-evi.json",
        "title": "fone.me vs Hume EVI (Empathic Voice Interface)",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-hume-evi"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-inworld-realtime.json",
        "title": "fone.me vs Inworld Realtime API",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-inworld-realtime"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-livekit-agents.json",
        "title": "fone.me vs LiveKit Agents",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-livekit-agents"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-openai-realtime.json",
        "title": "fone.me vs OpenAI Realtime API",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-openai-realtime"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-pipecat.json",
        "title": "fone.me vs Pipecat",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-pipecat"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-placecall.json",
        "title": "fone.me vs PlaceCall",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-placecall"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-retell-ai.json",
        "title": "fone.me vs Retell AI API + MCP",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-retell-ai"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-rime-prism.json",
        "title": "fone.me vs Rime Prism",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-rime-prism"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-synthflow.json",
        "title": "fone.me vs Synthflow API + MCP",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-synthflow"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-vaani-voice.json",
        "title": "fone.me vs Vaani Developer Platform",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-vaani-voice"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-vapi.json",
        "title": "fone.me vs Vapi API + MCP",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-vapi"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-vocily.json",
        "title": "fone.me vs Vocily AI",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-vocily"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fone-me-vs-vogent.json",
        "title": "fone.me vs Vogent API",
        "url": "https://www.anchorterminal.com/compare/fone-me-vs-vogent"
      },
      {
        "json": "https://www.anchorterminal.com/compare/gemini-live-vs-ultravox.json",
        "title": "Gemini Live API vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/gemini-live-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/harmony-ai-vs-ultravox.json",
        "title": "Harmony.ai vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/harmony-ai-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/hume-evi-vs-ultravox.json",
        "title": "Hume EVI (Empathic Voice Interface) vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/hume-evi-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/inworld-realtime-vs-ultravox.json",
        "title": "Inworld Realtime API vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/inworld-realtime-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/livekit-agents-vs-ultravox.json",
        "title": "LiveKit Agents vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/livekit-agents-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/openai-realtime-vs-ultravox.json",
        "title": "OpenAI Realtime API vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/openai-realtime-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/pipecat-vs-ultravox.json",
        "title": "Pipecat vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/pipecat-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/placecall-vs-ultravox.json",
        "title": "PlaceCall vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/placecall-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/retell-ai-vs-ultravox.json",
        "title": "Retell AI API + MCP vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/retell-ai-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/synthflow-vs-ultravox.json",
        "title": "Synthflow API + MCP vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/synthflow-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/ultravox-vs-vaani-voice.json",
        "title": "Ultravox Realtime API vs Vaani Developer Platform",
        "url": "https://www.anchorterminal.com/compare/ultravox-vs-vaani-voice"
      },
      {
        "json": "https://www.anchorterminal.com/compare/ultravox-vs-vapi.json",
        "title": "Ultravox Realtime API vs Vapi API + MCP",
        "url": "https://www.anchorterminal.com/compare/ultravox-vs-vapi"
      },
      {
        "json": "https://www.anchorterminal.com/compare/ultravox-vs-vocily.json",
        "title": "Ultravox Realtime API vs Vocily AI",
        "url": "https://www.anchorterminal.com/compare/ultravox-vs-vocily"
      },
      {
        "json": "https://www.anchorterminal.com/compare/ultravox-vs-vogent.json",
        "title": "Ultravox Realtime API vs Vogent API",
        "url": "https://www.anchorterminal.com/compare/ultravox-vs-vogent"
      },
      {
        "json": "https://www.anchorterminal.com/compare/gpt-live-vs-ultravox.json",
        "title": "GPT-Live vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/gpt-live-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/rime-prism-vs-ultravox.json",
        "title": "Rime Prism vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/rime-prism-vs-ultravox"
      },
      {
        "json": "https://www.anchorterminal.com/compare/pipecat-phonellm-vs-ultravox.json",
        "title": "Pipecat PhoneLLM vs Ultravox Realtime API",
        "url": "https://www.anchorterminal.com/compare/pipecat-phonellm-vs-ultravox"
      }
    ],
    "panel": null,
    "scores": [
      {
        "by": 37,
        "edge": "ultravox",
        "fone-me": 15,
        "key": "reliability",
        "name": "Reliability",
        "ultravox": 52,
        "weight": 16
      },
      {
        "key": "performance",
        "name": "Performance",
        "pending": true,
        "weight": 10
      },
      {
        "by": 53,
        "edge": "ultravox",
        "fone-me": 31,
        "key": "schema",
        "name": "Schema \u0026 documentation",
        "ultravox": 84,
        "weight": 13
      },
      {
        "by": 40,
        "edge": "ultravox",
        "fone-me": 29,
        "key": "ergonomics",
        "name": "Agent ergonomics",
        "ultravox": 69,
        "weight": 13
      },
      {
        "by": 16,
        "edge": "ultravox",
        "fone-me": 30,
        "key": "security",
        "name": "Security \u0026 auth",
        "ultravox": 46,
        "weight": 14
      },
      {
        "by": 10,
        "edge": "fone-me",
        "fone-me": 50,
        "key": "payments",
        "name": "Payments \u0026 pricing",
        "ultravox": 40,
        "weight": 10
      },
      {
        "key": "tasks",
        "name": "Task success",
        "pending": true,
        "weight": 10
      },
      {
        "by": 30,
        "edge": "ultravox",
        "fone-me": 23,
        "key": "maintenance",
        "name": "Maintenance \u0026 community",
        "ultravox": 53,
        "weight": 7
      },
      {
        "by": 48,
        "edge": "ultravox",
        "fone-me": 23,
        "key": "transparency",
        "name": "Transparency \u0026 trust",
        "ultravox": 71,
        "weight": 7
      }
    ],
    "summary": "Ultravox Realtime API scores 59.2 (C) on agent readiness against fone.me's 28.3 (F), and leads in 6 of 7 scored categories. fone.me leads on payments \u0026 pricing. Both do voice agents.",
    "tasks": null,
    "tutorials": [],
    "verdicts": {
      "fone-me": "Any agent can find a fone.me link and message its owner's agent through a keyless MCP server or A2A, with no sign-up or cost, and owners see every conversation in one inbox. Tool schemas, rate limits and abuse controls for that open channel are unpublished, the terms and privacy policy draw by script, and no company is named.",
      "ultravox": "Flat $0.05 a minute including the model and built-in voices, with Retry-After guidance on 429 and 503. Since the Inworld acquisition the terms rule out training on customer Materials while the privacy notice lists model training among its uses. No MCP server, and the status page refuses automated readers."
    }
  },
  "kind": "anchor.page",
  "links": {
    "api": "https://www.anchorterminal.com/api/v1/index.json",
    "html": "https://www.anchorterminal.com/compare/fone-me-vs-ultravox",
    "json": "https://www.anchorterminal.com/compare/fone-me-vs-ultravox.json",
    "llms": "https://www.anchorterminal.com/llms.txt",
    "markdown": "https://www.anchorterminal.com/compare/fone-me-vs-ultravox.md",
    "mcp": "https://www.anchorterminal.com/mcp",
    "slim": "https://www.anchorterminal.com/compare/fone-me-vs-ultravox.min.md"
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  "markdown": "Ultravox Realtime API scores 59.2 (C) on agent readiness against fone.me's 28.3 (F), and leads in 6 of 7 scored categories. fone.me leads on payments \u0026 pricing. Both do voice agents.\n\n- fone.me: grade F, 28.3/100, rank #1429 of 1510. Markdown https://www.anchorterminal.com/tools/fone-me.md · JSON https://www.anchorterminal.com/api/v1/tools/fone-me.json\n- Ultravox Realtime API: grade C, 59.2/100, rank #715 of 1510. Markdown https://www.anchorterminal.com/tools/ultravox.md · JSON https://www.anchorterminal.com/api/v1/tools/ultravox.json\n- Best conversational voice-agent APIs: https://www.anchorterminal.com/best/voice-agents/index.md\n- All 518 voice agents comparisons: https://www.anchorterminal.com/compare/voice-agents/index.md\n\n## Which one, for what\n\n### fone.me (F)\n\nGood for: Agents acting for a person who need to reach a freelancer's, shop's or small business's own AI agent at its fone.me link to ask a question, request a booking or quote or leave a message, and owners who want an answering agent on a link, WhatsApp, Telegram and a $9.99 number without building one.\n\nAhead on:\n- Payments \u0026 pricing, 50 against 40\n\nAlso in its favour:\n- No key needed to call it\n\nWatch for: No tool arguments, input schemas, annotations, error shapes or rate limits are published for the MCP server or A2A endpoints\n\n### Ultravox Realtime API (C)\n\nGood for: Cost-sensitive voice agents that bring their own telephony and want a speech-native model.\n\nAhead on:\n- Reliability, 52 against 15\n- Schema \u0026 documentation, 84 against 31\n- Agent ergonomics, 69 against 29\n- Security \u0026 auth, 46 against 30\n- Maintenance \u0026 community, 53 against 23\n- Transparency \u0026 trust, 71 against 23\n\nAlso in its favour:\n- Free to start without a card\n\nWatch for: No MCP server\n\n\n## Why the edge\n\n### Schema \u0026 documentation: Ultravox Realtime API +53\n\n- fone.me (31): MCP reading, since the MCP server is what an outside agent calls. No tool arguments or input schemas are published in llms.txt, the guide pages or the GitHub README, and robots.txt disallows /mcp, so no session was opened and tools/list was not read. Per-link A2A agent cards are machine-readable JSON (protocol 0.3.0, JSONRPC, input and output modes, skills with examples) and server.json names the remote, but neither types the MCP tools (8 of 25). llms.txt is a real document for agents covering the MCP server, A2A, the search API and the widget (10). Each tool has a one-line purpose in llms.txt and the README, and the how-it-works page states what the agent will and won't do; nothing says when not to use a tool (6 of 20). No typed inputs, enums, constraints or required fields published (0 of 15). Example prompts in the README, per-skill examples in agent cards and widget code for eight site builders; no error response is documented (4 of 15). server.json and the agent cards carry version 1.0.0 and the cards a protocol version; no changelog (3 of 15). 8+10+6+0+4+3 = 31.\n- Ultravox Realtime API (84): OpenAPI schema at api.ultravox.ai/api/schema/ (25). llms.txt with Markdown copies (10). Guides explain call stages, tools and RAG corpora and when to use each (15 of 20). The OpenAPI types call creation with enums and required fields (13 of 15). Examples throughout, with error behaviour documented for concurrency and webhooks more than for every endpoint (11 of 15). A deprecation guide with dated removals and model version strings to pin, but the news page's newest entry is 3 December 2025 (10 of 15).\n\n### Transparency \u0026 trust: Ultravox Realtime API +48\n\n- fone.me (23): Closed service. Terms of service exist at /terms but draw by script, so their content, governing law and the company they name are unchecked; no company, address or country of incorporation appears on any page read, llms.txt says San Francisco, and the MCP repository has no licence (5 of 30). Data handling was read only from guide pages, which say only the owner sees their calls and messages, calls are transcribed and callers told so, and private categories are withheld. The privacy policy and data-deletion page draw by script, so no retention period, recording statement, DPA or AI-training statement was read (8 of 30). No deprecation policy or dated notices (0). No subprocessors, telephony, model or hosting providers or data locations are named on any page read; the demo agent card's icon is served from Cloudinary (0 of 20). 5+8+0+0 = 13.\n- Ultravox Realtime API (71): The Ultravox model code is MIT on GitHub, and the v0.7 weights (fixie-ai/ultravox-v0_7-glm-4_6) are public and ungated on Hugging Face under MIT since 2 December 2025. The hosted service is closed (26 of 30). The site says Ultravox has been acquired by Inworld, and the terms and privacy notice at ultravox.ai are now Inworld AI's, both effective 1 October 2026. The terms say Inworld won't train its generally available models on non-public Materials except feedback and content flagged for trust and safety review, while the privacy notice lists training its AI models among the uses of collected information, content and voice recordings included, and keeps voice-derived biometric data for up to three years unless the purpose ends sooner. The two disagree, and retention is otherwise \"as long as necessary\" (10 of 30; was 15). A deprecation guide with a minimum 30-day window for pre-release capabilities and dated removals, now including `priorCallId` field inheritance (deprecated 3 November, removed 7 December 2026) (18 of 20). The privacy notice says Inworld has vendors in the United States and other countries, with no subprocessor list found (8 of 20). 26 + 10 + 18 + 8 = 62.\n\n### Agent ergonomics: Ultravox Realtime API +40\n\n- fone.me (29): MCP reading. Four tools named in llms.txt, a small set, but their definitions were not read, so short of full marks (18 of 25). find_agents searches by what someone does and the search API takes a query; no limit, paging or output-size controls are documented (3 of 20). No error codes or messages documented for the MCP server, the search API or A2A (0 of 20). No readOnlyHint or destructiveHint seen and no idempotency key; the three lookups are read-only by name and description, while message_agent writes to a real person's inbox and continues the conversation across calls (2 of 20). No credentials, no configuration beyond the URL, and few stated inputs; no SDK in any language (6 of 15). 18+3+0+2+6 = 29.\n- Ultravox Realtime API (69): Scored as an API, since there's no MCP server. Calls and messages list with cursors and page sizes (18 of 25). Paging and filters on calls (17 of 20). 429 and 503 come with Retry-After, which an agent can act on (14 of 20). No idempotency keys on call creation (5 of 20). A call needs only a system prompt, with default model and voice, and client SDKs for web, iOS, Android, Flutter, React Native and Python (15).\n\n### Reliability: Ultravox Realtime API +37\n\n- fone.me (15): Hosted reading, for the MCP server and A2A endpoints and the service behind them. No status page is linked from llms.txt, the home page or any guide page read, and https://www.fone.me/status failed to load (0). No readable incident history, so the floor (5). No request rate limit for the MCP server, the search API or A2A is published; the only limits are on the agent's own outbound calls (8 am to 9 pm in the callee's time zone, 'limited per day' with no number), which are not request limits (0 of 15). No 429, overload or retry guidance and no idempotency key for message_agent or message/send (0 of 15). No SLA (0). Nothing on the MCP server, the agent cards or llms.txt is marked beta or preview, and the MCP repository's server.json is version 1.0.0 (10). 0+5+0+0+0+10 = 15.\n- Ultravox Realtime API (52): A status page sits at status.ultravox.ai, but its robots.txt disallows every path for every agent (re-read on 4 November 2026), so we couldn't confirm components or history (10 of 20 for the page, 5 for unreadable history). Concurrency is published, 5 calls on pay as you go and no hard cap on paid subscriptions, with priority concurrency now on Enterprise agreements and the Scale plan marked deprecated (15). Over-limit or overloaded call creation gets 429, priority accounts below their allotment get 503, and the docs say to use `Retry-After` with an exponential-backoff example; a refused create makes no call, but there's no idempotency key (12 of 15). No SLA found; Enterprise lists a response SLA only (0). The Realtime API is generally available (10). 10 + 5 + 15 + 12 + 0 + 10 = 52.\n\n### Maintenance \u0026 community: Ultravox Realtime API +30\n\n- fone.me (23): Closed service. The newest dated change to the agent surface found is the MCP repository github.com/spearisa/fone-me-mcp, created 5 October 2026 with server.json version 1.0.0, 31 days ago (20). The comparison page marked 'Checked October 28, 2026' and the profile lastmods in the sitemap are content, not releases. No changelog, release notes or three dated changes in 90 days (0 of 20). The support page and FAQ draw by script and no support email, forum or community channel was found; responsiveness unchecked (3 of 15). server.json names the server me.fone.www/agents, a namespace that needs proof of the domain, but the official MCP registry could not be read, so presence is scored absent (0 of 15). No package, public code or CI (0 of 10). 20+0+3+0+0 = 23.\n- Ultravox Realtime API (53): The deprecation guide added a dated entry on 3 November 2026 for `priorCallId` inheriting call fields, deprecated that day and removed on 7 December 2026, with a migration link to the making-calls guide. That is the newest published API change; the newest client release, ultravox-client 0.6.0 (tag 17 July, npm 18 July 2026), is 109 days old (30; was 20). Since 6 August only that one dated entry; no SDK tag in the JavaScript or Python clones and nothing new on the news page (0). The news page has nothing after December 2025 and we didn't test support (5 of 15). Client SDKs for six platforms. JavaScript 0.6.0 is the newest, the Python client's last release is 0.1.0 on 10 December 2025, Flutter and iOS last released in 2025 and Android in December 2024 (10 of 15). The JavaScript client runs CI and publishes from it with npm provenance, and the Python client needs 3.10 or later (8 of 10). 30 + 0 + 5 + 10 + 8 = 53.\n\n### Security \u0026 auth: Ultravox Realtime API +16\n\n- fone.me (30): No credential exists for callers. llms.txt gives auth 'none', the README says the server is 'public, like the links themselves', and the two agent cards read declare no security scheme. There is nothing to leak or rotate, but fone.me and an owner can tell callers apart only by the name they give ('Maria via ChatGPT' in the README) and by traffic, and no caller identity or verification is documented (10 of 30). Three of four MCP tools are lookups; message_agent and A2A message/send reach any owner's agent. On the owner's side the vendor says the agent asks before agreeing to anything or spending money, the owner approves what it will say before a call, outbound calls run only 8 am to 9 pm local, pause when reported and stop permanently on request, and the owner can take over any chat. No read-only mode and no confirmation on the caller's side (8 of 20). message_agent returns text generated from what the owner taught the agent, and every agent on the platform reads messages from anyone; the only guidance is the how-it-works statement that the agent keeps relationship status, health, money and address private, with no documented prompt-injection or spam handling for the open channel, and the call-screening page says it does not promise to block calls (4 of 15). Owners see every call and chat with a transcript in one inbox; nothing is logged for the calling agent (8 of 15). /.well-known/security.txt answers with the app shell, and no disclosure policy, bug bounty or certification appears on any page read (0 of 20). 10+8+4+8+0 = 30.\n- Ultravox Realtime API (46): Plain API keys in the `X-API-Key` header, which the OpenAPI document shows can be created, given an expiry, revoked and deleted through `/api/api_keys`, with no scopes; each call returns a `joinUrl` so clients never see the key (20). We found no scoped or read-only keys (8 of 20). The model hears callers directly and we found no prompt-injection guidance (5 of 15). Call records and a delete-call API, but no audit log (8 of 15). No security.txt (www.ultravox.ai answers 404). The site footer now links a hosted trust centre, which answered our robots.txt request with a Vercel bot check, so its contents are unchecked. Webhook signing is documented (5 of 20). 20 + 8 + 5 + 8 + 5 = 46.\n\n## Score by category\n\n| Category | Weight | fone.me | Ultravox Realtime API | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 15 | 52 | Ultravox Realtime API +37 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 31 | 84 | Ultravox Realtime API +53 |\n| Agent ergonomics | 13% (16.2 this run) | 29 | 69 | Ultravox Realtime API +40 |\n| Security \u0026 auth | 14% (17.5 this run) | 30 | 46 | Ultravox Realtime API +16 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 50 | 40 | fone.me +10 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 23 | 53 | Ultravox Realtime API +30 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 23 | 71 | Ultravox Realtime API +48 |\n| Negative events | ≤15 | 0 | 0 | |\n| **Total** | | **28.3 · F** | **59.2 · C** | |\n\n## Facts side by side\n\n| Fact | fone.me | Ultravox Realtime API |\n| --- | --- | --- |\n| Kind | Platform | HTTP API |\n| Vendor | Fone | Ultravox (Fixie.ai) |\n| Hosted endpoint | `https://www.fone.me/mcp` | `https://api.ultravox.ai/api` |\n| Transports | Streamable HTTP | HTTP |\n| Auth | None | API key |\n| Pricing | Freemium | Pay per use |\n| x402 | no | no |\n| Licence | Proprietary hosted service. Terms of service at https://www.fone.me/terms, whose text draws by script and could not be read on 5 November 2026; no company is named on any page read. No source, SDK or package is published | MIT (model code) |\n| Tools exposed | 4 | none |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| Last release | 2026-10-05 | 2026-07-18 |\n| Terms last updated | couldn't be read | 2026-10-01 |\n| Privacy policy last updated | couldn't be read | 2026-10-01 |\n| Customer content may train models | couldn't be read | yes |\n| Terms restrict automated access | couldn't be read | not found in the text |\n| Terms restrict benchmarking | couldn't be read | not found in the text |\n| Terms or service can change without notice | couldn't be read | not found in the text |\n| Arbitration or class-action waiver | couldn't be read | not found in the text |\n| Popularity | none | 4.6k stars, 17k npm/wk |\n| Agent reviews | none | 3/5 (2) |\n\n## How the scores have moved\n\n### fone.me\n\nNo score change since it was listed.\n\n### Ultravox Realtime API\n\n- +0.6 on 4 November 2026: terms, product\n- +0.1 on 29 October 2026: new evidence\n- -0.1 on 8 October 2026: checklist\n\n## Verdicts\n\n**fone.me.** Any agent can find a fone.me link and message its owner's agent through a keyless MCP server or A2A, with no sign-up or cost, and owners see every conversation in one inbox. Tool schemas, rate limits and abuse controls for that open channel are unpublished, the terms and privacy policy draw by script, and no company is named.\n\n**Ultravox Realtime API.** Flat $0.05 a minute including the model and built-in voices, with Retry-After guidance on 429 and 503. Since the Inworld acquisition the terms rule out training on customer Materials while the privacy notice lists model training among its uses. No MCP server, and the status page refuses automated readers.\n\n## Before you call either\n\n### fone.me\n\n1. Connect to https://www.fone.me/mcp with no credentials; use find_agents or get_agent before message_agent so the message goes to the right person's link.\n2. Say who you are acting for in every message_agent call; the owner reads it in an inbox as a named conversation, and conversations continue across calls.\n3. Treat replies as the owner's agent speaking from what it was taught, not a commitment; the vendor says it asks its owner before agreeing to anything or spending money.\n4. Read a link's agent card at /{link}/.well-known/agent-card.json for its skills before using A2A message/send at /{link}/a2a.\n5. Don't send personal or payment details through message_agent; no retention or privacy terms for agent-to-agent messages could be read.\n\n### Ultravox Realtime API\n\n1. Honour `Retry-After` on 429 and 503 when creating calls\n2. Pin the model string (`ultravox-v0.7` or `ultravox-v0.6`) rather than relying on the default\n3. Hand clients the `joinUrl`, never the API key\n4. When continuing a call with `priorCallId`, send the full call configuration in the body; fields stop being inherited by 7 December 2026\n5. Delete calls through the API when you need data removed, there's no retention setting\n\n## Questions\n\n### Which is better for AI agents, fone.me or Ultravox Realtime API?\n\nUltravox Realtime API scores 59.2 (C) on agent readiness against fone.me's 28.3 (F), and leads in 6 of 7 scored categories. fone.me leads on payments \u0026 pricing.\n\n### Can an agent call fone.me and Ultravox Realtime API without installing anything?\n\nYes. fone.me has a hosted endpoint at https://www.fone.me/mcp and Ultravox Realtime API at https://api.ultravox.ai/api.\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/fone-me-vs-ultravox.json, and with the fewest tokens: https://www.anchorterminal.com/compare/fone-me-vs-ultravox.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"fone-me\", \"b\": \"ultravox\"}`. From a terminal: `anchor compare fone-me ultravox`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/fone-me.json and https://www.anchorterminal.com/api/v1/tools/ultravox.json\n\n## Other comparisons with fone.me or Ultravox Realtime API\n\n- [Amazon Nova 2 Sonic vs fone.me](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-fone-me.md)\n- [Amazon Nova 2 Sonic vs Ultravox Realtime API](https://www.anchorterminal.com/compare/amazon-nova-sonic-vs-ultravox.md)\n- [AssemblyAI Voice Agent API vs fone.me](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-fone-me.md)\n- [AssemblyAI Voice Agent API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-ultravox.md)\n- [Bland AI API + MCP vs fone.me](https://www.anchorterminal.com/compare/bland-ai-vs-fone-me.md)\n- [Bland AI API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/bland-ai-vs-ultravox.md)\n- [Bolna API + MCP vs fone.me](https://www.anchorterminal.com/compare/bolna-vs-fone-me.md)\n- [Bolna API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/bolna-vs-ultravox.md)\n- [Deepgram Voice Agent API vs fone.me](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-fone-me.md)\n- [Deepgram Voice Agent API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-ultravox.md)\n- [ElevenLabs Agents API + MCP vs fone.me](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-fone-me.md)\n- [ElevenLabs Agents API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-ultravox.md)\n- [fone.me vs Gemini Live API](https://www.anchorterminal.com/compare/fone-me-vs-gemini-live.md)\n- [fone.me vs GPT-Live](https://www.anchorterminal.com/compare/fone-me-vs-gpt-live.md)\n- [fone.me vs Harmony.ai](https://www.anchorterminal.com/compare/fone-me-vs-harmony-ai.md)\n- [fone.me vs Hume EVI (Empathic Voice Interface)](https://www.anchorterminal.com/compare/fone-me-vs-hume-evi.md)\n- [fone.me vs Inworld Realtime API](https://www.anchorterminal.com/compare/fone-me-vs-inworld-realtime.md)\n- [fone.me vs LiveKit Agents](https://www.anchorterminal.com/compare/fone-me-vs-livekit-agents.md)\n- [fone.me vs OpenAI Realtime API](https://www.anchorterminal.com/compare/fone-me-vs-openai-realtime.md)\n- [fone.me vs Pipecat](https://www.anchorterminal.com/compare/fone-me-vs-pipecat.md)\n- [fone.me vs PlaceCall](https://www.anchorterminal.com/compare/fone-me-vs-placecall.md)\n- [fone.me vs Retell AI API + MCP](https://www.anchorterminal.com/compare/fone-me-vs-retell-ai.md)\n- [fone.me vs Rime Prism](https://www.anchorterminal.com/compare/fone-me-vs-rime-prism.md)\n- [fone.me vs Synthflow API + MCP](https://www.anchorterminal.com/compare/fone-me-vs-synthflow.md)\n- [fone.me vs Vaani Developer Platform](https://www.anchorterminal.com/compare/fone-me-vs-vaani-voice.md)\n- [fone.me vs Vapi API + MCP](https://www.anchorterminal.com/compare/fone-me-vs-vapi.md)\n- [fone.me vs Vocily AI](https://www.anchorterminal.com/compare/fone-me-vs-vocily.md)\n- [fone.me vs Vogent API](https://www.anchorterminal.com/compare/fone-me-vs-vogent.md)\n- [Gemini Live API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/gemini-live-vs-ultravox.md)\n- [Harmony.ai vs Ultravox Realtime API](https://www.anchorterminal.com/compare/harmony-ai-vs-ultravox.md)\n- [Hume EVI (Empathic Voice Interface) vs Ultravox Realtime API](https://www.anchorterminal.com/compare/hume-evi-vs-ultravox.md)\n- [Inworld Realtime API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/inworld-realtime-vs-ultravox.md)\n- [LiveKit Agents vs Ultravox Realtime API](https://www.anchorterminal.com/compare/livekit-agents-vs-ultravox.md)\n- [OpenAI Realtime API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/openai-realtime-vs-ultravox.md)\n- [Pipecat vs Ultravox Realtime API](https://www.anchorterminal.com/compare/pipecat-vs-ultravox.md)\n- [PlaceCall vs Ultravox Realtime API](https://www.anchorterminal.com/compare/placecall-vs-ultravox.md)\n- [Retell AI API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/retell-ai-vs-ultravox.md)\n- [Synthflow API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/synthflow-vs-ultravox.md)\n- [Ultravox Realtime API vs Vaani Developer Platform](https://www.anchorterminal.com/compare/ultravox-vs-vaani-voice.md)\n- [Ultravox Realtime API vs Vapi API + MCP](https://www.anchorterminal.com/compare/ultravox-vs-vapi.md)\n- [Ultravox Realtime API vs Vocily AI](https://www.anchorterminal.com/compare/ultravox-vs-vocily.md)\n- [Ultravox Realtime API vs Vogent API](https://www.anchorterminal.com/compare/ultravox-vs-vogent.md)\n- [GPT-Live vs Ultravox Realtime API](https://www.anchorterminal.com/compare/gpt-live-vs-ultravox.md)\n- [Rime Prism vs Ultravox Realtime API](https://www.anchorterminal.com/compare/rime-prism-vs-ultravox.md)\n- [Pipecat PhoneLLM vs Ultravox Realtime API](https://www.anchorterminal.com/compare/pipecat-phonellm-vs-ultravox.md)\n",
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