# Best phone calling and voice transport APIs for AI agents (slim)

> Twilio Programmable Voice API + MCP (A), Telnyx Voice API + MCP (BB) and LiveKit Telephony (B) lead the 13 ranked phone calling and voice transport APIs. Picks by need, strengths, weaknesses and prices from the Anchor benchmark.

- Full: https://www.anchorterminal.com/best/voice-calling/index.md (~5,600 tokens) · this version ~1,480 tokens · JSON https://www.anchorterminal.com/best/voice-calling/index.json · canonical https://www.anchorterminal.com/best/voice-calling/
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-09

The 10 highest-scoring of 13 phone calling and voice transport APIs on the Anchor benchmark, with a pick for each need and where each one falls short. Scores come from public evidence, re-checked as vendors change.

- Ranked: 13 · agent-ready (BB or better): 2 · accept x402: 0 · hosted endpoints: 10
- Full ranked table: https://www.anchorterminal.com/categories/voice-calling.md
- Head-to-head comparisons: https://www.anchorterminal.com/compare/voice-calling/index.md (78)
- Methodology: https://www.anchorterminal.com/benchmark/index.md

## The shortlist

| # | Tool | Grade | Score | Best for | Price | Where |
| --- | --- | --- | --- | --- | --- | --- |
| 1 | [Twilio Programmable Voice API + MCP](https://www.anchorterminal.com/tools/twilio-voice.md) | A | 80.4 | Teams that want the widest number coverage and a managed speech layer (ConversationRelay) behind one vendor, or a published SLA. | $1.15 / mo | hosted and local |
| 2 | [Telnyx Voice API + MCP](https://www.anchorterminal.com/tools/telnyx-voice.md) | BB | 74.2 | Cost-sensitive US outbound voice agents and for agents that must onboard and pay without a person. | $1 / mo | hosted and local |
| 3 | [LiveKit Telephony](https://www.anchorterminal.com/tools/livekit-telephony.md) | B | 67.5 | Teams that already run voice agents on LiveKit and want phone calls to arrive in the same rooms, bringing their own carrier for outbound and international calls. | $1 / mo | local |
| 4 | [SignalWire Voice API](https://www.anchorterminal.com/tools/signalwire-voice.md) | B | 67.1 | Builders who want call logic in documents (SWML) or a hosted AI agent verb, and for teams moving off Twilio's API shape. | $0.50 / mo | local |
| 5 | [DIDWW Voice and Number Management API](https://www.anchorterminal.com/tools/didww-voice-and-number-management.md) | B | 65.1 | Teams that run their own SIP system, or a voice agent platform that accepts SIP trunks, and need numbers in many countries with compliance records handled through an API. | Pay per use | hosted |
| 6 | [Bandwidth Voice API + MCP](https://www.anchorterminal.com/tools/bandwidth-voice.md) | B | 63.7 | US and Canada outbound voice agents that need capacity from day one and a carrier-owned network. | Pay per use | hosted and local |
| 7 | [Sinch Voice API + MCP](https://www.anchorterminal.com/tools/sinch-voice.md) | B | 62.7 | Teams already on Sinch messaging, or voice agents that want a managed STT and TTS relay with barge-in without running their own speech stack. | Pay per use | hosted and local |
| 8 | [Plivo Voice API](https://www.anchorterminal.com/tools/plivo-voice.md) | C | 60.4 | Cost-sensitive voice agents built on Pipecat, LiveKit, Vapi or Retell, and for India traffic. | $0.50 / mo | hosted |
| 9 | [Infobip Calls API + MCP](https://www.anchorterminal.com/tools/infobip-calls.md) | C | 60.3 | Teams already on Infobip messaging, or that need one vendor for PSTN, SIP, WebRTC and WhatsApp calling across many countries with tightly scoped keys. | Pay per use | hosted |
| 10 | [Vonage Voice API + MCP](https://www.anchorterminal.com/tools/vonage-voice.md) | C | 58.9 | Voice agents that want 16 or 24 kHz linear PCM over the websocket and per-second billing. | Pay per use | hosted and local |

## Picks by need

- Highest score overall: [Twilio Programmable Voice API + MCP](https://www.anchorterminal.com/tools/twilio-voice.md), A, 80.4/100 on the benchmark. Also [Telnyx Voice API + MCP](https://www.anchorterminal.com/tools/telnyx-voice.md), BB, 74.2/100.
- Schema & documentation: [Telnyx Voice API + MCP](https://www.anchorterminal.com/tools/telnyx-voice.md), 93/100 on schema & documentation, against 92 for the overall leader.
- Agent ergonomics: [Telnyx Voice API + MCP](https://www.anchorterminal.com/tools/telnyx-voice.md), 90/100 on agent ergonomics, against 80 for the overall leader.
- Maintenance & community: [LiveKit Telephony](https://www.anchorterminal.com/tools/livekit-telephony.md), 90/100 on maintenance & community, against 85 for the overall leader.
- Self-hosting under an open licence: [jambonz](https://www.anchorterminal.com/tools/jambonz.md), self-hosted, Proprietary licence.
- The review panel's favourite: [Telnyx Voice API + MCP](https://www.anchorterminal.com/tools/telnyx-voice.md), 3.5/5 from 8 panel reviews.

## How to choose

- Number availability by country: Check which countries and number types are available, since an agent cannot place or receive calls in a country where you cannot buy a number.
- Webhook reliability and retries: Check whether call events are retried when your endpoint is down and arrive in order, since a missed hang-up can leave the agent holding a dead call.
- Audio streaming over websocket or SIP: Check whether bidirectional audio streams over a websocket or SIP trunk, and what codec and sample rate you receive, since a mismatch adds delay or garbled speech.
- Full cost of a call: Price a complete call including connection, per-minute, recording, transfer and speech charges, because the headline rate may cover only part of the bill.

- How the benchmark tests this category: Inbound and outbound call setup, bidirectional audio streaming, a warm transfer and a recording on every API. We watch webhook reliability, note which countries numbers are available in, and price a five-minute call end to end.

Each listing's verdict, strengths and weaknesses: https://www.anchorterminal.com/best/voice-calling/index.md