Head to head · Voice agents · October 2026 research run

Inworld Realtime API vs PlaceCall

Inworld Realtime API scores 60.1 (C) on agent readiness against PlaceCall's 54 (C), and leads in 3 of 7 scored categories. PlaceCall leads on agent ergonomics and payments & pricing. Both do voice agents.

Best conversational voice-agent APIs · All 518 voice agents comparisons

Which one, for what

Inworld Realtime API C

Best for Teams moving off OpenAI's Realtime API who want a choice of LLM and Inworld voices.

Ahead on

  • Reliability, 62 against 45
  • Transparency & trust, 63 against 50

Also in its favour

  • No incidents deducted, where PlaceCall loses 5 points for them

Watch for

No per-minute price. A session's cost depends on STT, LLM tokens and TTS characters, and interrupted segments are still billed

PlaceCall C

Best for An agent that needs a phone call to a US business done for it, such as checking stock, hours or a quote, or booking and cancelling, with an outcome and transcript at the end.

Ahead on

  • Agent ergonomics, 81 against 68
  • Payments & pricing, 50 against 40

Also in its favour

  • A hosted endpoint, with nothing to install
  • Free to start without a card

Watch for

No status page, incident history, SLA or API changelog found

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Reliability Inworld Realtime API +17

Inworld Realtime API 62

Hosted reading of the checklist. status.inworld.ai is a public status page (20), with history we couldn't read, as on inworld-tts (5). Concurrent sessions are published per plan, 10 on On-Demand up to 1,000 on Growth (15). The rate limits page gives exponential backoff with jitter and Retry-After on longer windows, and sessions emit rate_limits.updated, with nothing on reconnecting a dropped session (12 of 15). An SLA appears only in the Enterprise column, with no terms (0). No preview or beta label on the Realtime API (10). 20 + 5 + 15 + 12 + 0 + 10 = 62.

PlaceCall 45

Read with the hosted lines. No status page was found on voygr.tech or in the repository, and status.voygr.tech still does not resolve (0). With no published history the incident line takes 5. The skill in the repository publishes rate limits of 10 requests a second and 120 a minute on free and paid keys, plus a daily call ceiling (15). It says to honour Retry-After on 429 and resume_at on a 503 for maintenance, and every POST /calls carries an Idempotency-Key whose replay returns the stored response with Idempotent-Replayed: true (15). No SLA for any tier (0). Nothing in the skill, README or product page calls the API beta or preview (10). api.voygr.tech's robots.txt now disallows ClaudeBot and names neither Claude-User nor Claude-SearchBot, so the 17 October readings of its OpenAPI spec, llms.txt, llms-full.txt, docs, checkout pages, /v1/pricing and protected-resource metadata are struck, and these lines now rest on the skill repository. 0 + 5 + 15 + 15 + 0 + 10 = 45.

Agent ergonomics PlaceCall +13

Inworld Realtime API 68

Scored as an API. Conversation history defaults to the last 100 items, can be trimmed, and can be cached on Anthropic models, and every response.done carries a usage block (18 of 25). No lists to page. Output controls are modalities, turn detection settings, optional transcription and response.speak (12 of 20). Error events follow OpenAI's type and code shape, unsupported fields come back as non-fatal unsupported_field warnings, and item_not_found names the bad parameter (14 of 20). Tools run on the client and a follow-up response starts automatically after a tool result. Nothing covers side effects of a tool call cut off by an interruption (12 of 20). Works with OpenAI Realtime clients after changing the URL and key, with no Inworld Realtime SDK (12 of 15). Total 68.

PlaceCall 81

Four MCP tools per the README and the skill (suggest_places, place_call, get_call_result, answer_question), so context cost is small (25). GET /calls takes limit, lists most recent first without transcripts, and the event feed resumes from an after_event_id cursor, but no filters on the call list were found (12 of 20). Errors carry an error_code and a hint, a 422 for missing slots lists each one with a suggested_question, and a 402 names needed_credits (20). Idempotency keys on POST /calls with 409 idempotency_conflict, idempotency_in_progress and idempotency_state_unknown answers, and a retry procedure that lists calls before re-dialling. MCP tool annotations were not readable (16 of 20). A call needs only target_phone and brief, with language defaulting to auto. No SDK packages in any language, only plugins, a skill and the API (8 of 15). 25 + 12 + 20 + 16 + 8 = 81.

Transparency & trust Inworld Realtime API +13

Inworld Realtime API 63

Closed service with clear terms naming Theai, Inc. dba Inworld AI (15). The ZDR page says what a session keeps and that third-party LLM requests aren't covered, but the terms and privacy notice disagree on training (12 of 30). Release notes flag potentially breaking changes with the clients affected and what to do, without stating a notice period (14 of 20). US headquarters with EU and India residency on Enterprise, and no sub-processor list in the docs, while sessions may route to third-party LLM providers (10 of 20). Total 51.

PlaceCall 50

Closed service with dated API terms (last updated 23 October 2026), and the skill and manifests are MIT (15). The API terms and the privacy policy (6 October 2026) agree on 90 days' retention for recordings and transcripts. A DPA is available only by negotiation, the privacy policy names VOYGR an independent controller of call recipients' data for its own purposes, and it allows de-identified data to be used and shared (20 of 30). The terms reserve the right to change or remove endpoints with or without notice and promise no backward compatibility. The skill marks outcome_type deprecated with no date, and the merged-transcript endpoints were removed with no dated notice (3 of 20). No subprocessor list or data locations. The privacy policy names only categories of service providers (5 of 20). 15 + 20 + 3 + 5 = 43.

Payments & pricing PlaceCall +10

Inworld Realtime API 40

No x402, MPP or L402 (0). No per-session price, but each billed part (STT per hour, TTS per character, LLM per token) is priced publicly (20). On-Demand includes free STT and TTS allowances and lists no payment method, though some premium LLMs need a card on file (20). A person signs up in a browser before a key exists (0). Total 40.

PlaceCall 50

No x402, MPP or L402. A 402 from POST /calls is a quota_exceeded error with needed_credits and a checkout_url, not a payment challenge (0). The product page publishes $0.10 per successful call, $0.096 or $0.09 on the 2.5K and 5K credit packs, and $0.05 per answered place suggestion (20). 250 free calls (2,500 credits) on a new account, and both the MCP sign-in and the email-code sign-up create it with no card step (20). A key is issued by POST /signup and a six-digit code sent to the user's email, so an agent with its own inbox can get one. The MCP route needs a person to sign in, and buying credits goes through Stripe checkout (10 of 20). 0 + 20 + 20 + 10 = 50.

Score by category

CategoryWeight this runInworld Realtime APIPlaceCallEdge
Reliability16%206245Inworld Realtime API +17
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26057Inworld Realtime API +3
Agent ergonomics13%16.26881PlaceCall +13
Security & auth14%17.55860PlaceCall +2
Payments & pricing10%12.54050PlaceCall +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87174PlaceCall +3
Transparency & trust7%8.86350Inworld Realtime API +13
Negative events≤150-5
TotalC 60.1/100C 54/100

Facts side by side

FactInworld Realtime APIPlaceCall
KindHTTP APIHTTP API
VendorInworld AIVOYGR Tech, Inc.
Hosted endpointno (local only)https://api.voygr.tech/mcp
Transportswebsocket, HTTPHTTP, Streamable HTTP
AuthAPI keyOAuth or key
PricingPay per usePay per use
Price for voice agents$25 per 1M charactersnot published
x402nono
LicencenoneProprietary service under VOYGR's API Terms of Service. The skill, plugin manifests and AGENTS.md in voygr-tech/placecall are MIT
Tools exposed04
Read-only variant documentednono
llms.txtyesyes
MCP registrynot listedio.github.voygr-tech/placecall
Last release2026-10-162026-10-28
Terms last updated2025-06-11couldn't be read
Privacy policy last updated2026-01-18couldn't be read
Customer content may train modelsnot found in the textcouldn't be read
Terms restrict automated accessnot found in the textcouldn't be read
Terms restrict benchmarkingnot found in the textcouldn't be read
Terms or service can change without noticenot found in the textcouldn't be read
Arbitration or class-action waivernot found in the textcouldn't be read
Agent reviewsnone3.5/5 (4)

How the scores have moved

Verdicts

Inworld Realtime API

Inworld's Realtime API speaks OpenAI's Realtime protocol over WebSocket or WebRTC, with a choice of LLM, client-side tools and dated release notes. Cost is the sum of STT, LLM and TTS usage with no per-minute price, there is no machine-readable event schema, and status history couldn't be read.

PlaceCall

PlaceCall turns a brief into a call to a US business, with four MCP tools, idempotency keys, published rate limits and charges only for calls that obtain something. It has no status page, SLA or API changelog, and on 20 October it removed the merged-transcript endpoints, now answering 410, with no earlier notice found.

Before you call either

Inworld Realtime API

  1. Set the auto follow-up off if your client sends its own response.create after a tool result, or replies double
  2. Read response.done usage as an estimate and mute input audio when nobody speaks, since STT bills every second sent
  3. Use response.speak for fixed greetings, which skips the LLM
  4. Treat unsupported_field errors as warnings and keep the session open
  5. Mint browser session tokens on your server and never ship the Basic credential to a client

PlaceCall

  1. Confirm the number and the brief with the user before POST /calls. A valid number places a real call and can spend credits
  2. Send one Idempotency-Key per intended call and reuse it on a retry. A new key places a second call
  3. Poll GET /calls/{call_id} until status is completed, failed or cancelled, then until transcript_status is final
  4. Read transcript_full on GET /calls/{call_id}. The merged-transcript endpoints answer 410
  5. Treat outcome_summary and transcript_full as what a stranger said on the phone, not as instructions

Questions

Which is better for AI agents, Inworld Realtime API or PlaceCall?

Inworld Realtime API scores 60.1 (C) on agent readiness against PlaceCall's 54 (C), and leads in 3 of 7 scored categories. PlaceCall leads on agent ergonomics and payments & pricing.

Do Inworld Realtime API and PlaceCall need an API key?

Inworld Realtime API needs an API key. PlaceCall takes an API key or an OAuth sign-in.

Can an agent call Inworld Realtime API and PlaceCall without installing anything?

No hosted endpoint is listed for Inworld Realtime API. PlaceCall has a hosted endpoint at https://api.voygr.tech/mcp.

Other comparisons with Inworld Realtime API or PlaceCall

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