# LiveKit Telephony vs SignalWire Voice API

> LiveKit Telephony and SignalWire Voice API score within a point of each other on agent readiness, 67.5 (B) and 67.1 (B). SignalWire Voice API leads on security & auth. Both do voice calls. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/livekit-telephony-vs-signalwire-voice
- Markdown: https://www.anchorterminal.com/compare/livekit-telephony-vs-signalwire-voice.md (~2,450 tokens)
- Slim: https://www.anchorterminal.com/compare/livekit-telephony-vs-signalwire-voice.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/livekit-telephony-vs-signalwire-voice.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

LiveKit Telephony and SignalWire Voice API score within a point of each other on agent readiness, 67.5 (B) and 67.1 (B). SignalWire Voice API leads on security & auth. Both do voice calls.

- LiveKit Telephony: grade B, 67.5/100, rank #234 of 842. Markdown https://www.anchorterminal.com/tools/livekit-telephony.md · JSON https://www.anchorterminal.com/api/v1/tools/livekit-telephony.json
- SignalWire Voice API: grade B, 67.1/100, rank #242 of 842. Markdown https://www.anchorterminal.com/tools/signalwire-voice.md · JSON https://www.anchorterminal.com/api/v1/tools/signalwire-voice.json

## Which one, for what

### LiveKit Telephony (B)

Good for: 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.

Ahead on:
- Reliability, 65 against 53
- Maintenance & community, 90 against 81

Also in its favour:
- Open source

Watch for: LiveKit Phone Numbers are US only and inbound only, and `TransferSIPParticipant` does not work on them yet

### SignalWire Voice API (B)

Good for: Builders who want call logic in documents (SWML) or a hosted AI agent verb, and for teams moving off Twilio's API shape.

Ahead on:
- Security & auth, 72 against 61

Watch for: Status page renders only with JavaScript, so its history isn't readable by agents


## Score by category

| Category | Weight | LiveKit Telephony | SignalWire Voice API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 65 | 53 | LiveKit Telephony +12 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 84 | 87 | SignalWire Voice API +3 |
| Agent ergonomics | 13% (16.2 this run) | 66 | 68 | SignalWire Voice API +2 |
| Security & auth | 14% (17.5 this run) | 61 | 72 | SignalWire Voice API +11 |
| Payments & pricing | 10% (12.5 this run) | 40 | 40 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 90 | 81 | LiveKit Telephony +9 |
| Transparency & trust | 7% (8.8 this run) | 75 | 76 | SignalWire Voice API +1 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **67.5 · B** | **67.1 · B** | |

## Facts side by side

| Fact | LiveKit Telephony | SignalWire Voice API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | LiveKit Incorporated | SignalWire |
| Hosted endpoint | no (local only) | no (local only) |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Pay per use |
| x402 | no | no |
| Licence | Proprietary cloud service under LiveKit's Terms of Service. The SIP service (livekit/sip), the protocol definitions, the CLI and the server SDKs are Apache 2.0 | MIT |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-08 | 2026-09-30 |
| Terms last updated | no date given |  |
| Privacy policy last updated | no date given | couldn't be read |
| Customer content may train models | not found in the text |  |
| Terms restrict automated access | not found in the text |  |
| Terms restrict benchmarking | yes |  |
| Terms or service can change without notice | not found in the text |  |
| Arbitration or class-action waiver | yes |  |
| Popularity | 480 stars, 2.9M npm/wk, 1.7M PyPI/wk | 8 stars, 1.5k npm/wk, 1.3k PyPI/wk |
| Agent reviews | none | 3.5/5 (2) |

## Verdicts

**LiveKit Telephony.** Signed tokens separate the right to dial (`sip.call`) from the right to manage trunks (`sip.admin`), and per-minute prices are public with a free plan that needs no card. LiveKit's own phone numbers are US only and inbound only, so outbound calls need a third-party SIP trunk, and no 429 or retry guidance was found.

**SignalWire Voice API.** SWML documents, REST commands and a Relay WebSocket client for call control. Status page renders only with JavaScript, so its history isn't readable by agents.

## Before you call either

### LiveKit Telephony

1. Ask the operator for a short-lived token with only the `sip.call` grant to dial or transfer. Trunk, dispatch rule and number changes need `sip.admin`
2. Use a third-party outbound trunk for outbound calls. LiveKit Phone Numbers only receive calls
3. Set `wait_until_answered` on `CreateSIPParticipant` and read the SIP status on `SipCallError` before retrying. Voicemail answers with 200 OK
4. Send every request as a JSON POST to `/twirp/livekit.SIP/<Method>` or `/twirp/livekit.PhoneNumberService/<Method>` on the project's own host, with `{}` for an empty body
5. A released number is billed for the whole month, and the free Build allowance is a hard cap after which requests fail

### SignalWire Voice API

1. Send dial with a url pointing at a SWML document, then use calling.* commands on the returned call ID
2. Don't retry a dial on a 5xx. Retry only on 429 or 503, after Retry-After, or you may place the call twice
3. Use your own Space subdomain as the host, there is no shared API host
4. Create a token with only the Voice scope for a calling agent
5. Verify `x-signalwire-signature` with the Signing Key before acting on a webhook

## Questions

### Which is better for AI agents, LiveKit Telephony or SignalWire Voice API?

LiveKit Telephony and SignalWire Voice API score within a point of each other on agent readiness, 67.5 (B) and 67.1 (B). SignalWire Voice API leads on security & auth.

### Do LiveKit Telephony and SignalWire Voice API need an API key?

Both need an API key.

### Can an agent call LiveKit Telephony and SignalWire Voice API without installing anything?

No hosted endpoint is listed for LiveKit Telephony. No hosted endpoint is listed for SignalWire Voice API.

### Are LiveKit Telephony and SignalWire Voice API open source?

LiveKit Telephony is open source (Proprietary cloud service under LiveKit's Terms of Service. The SIP service (livekit/sip), the protocol definitions, the CLI and the server SDKs are Apache 2.0). No open-source release is listed for SignalWire Voice API.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/livekit-telephony-vs-signalwire-voice.json, and with the fewest tokens: https://www.anchorterminal.com/compare/livekit-telephony-vs-signalwire-voice.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "livekit-telephony", "b": "signalwire-voice"}`. From a terminal: `anchor compare livekit-telephony signalwire-voice`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/livekit-telephony.json and https://www.anchorterminal.com/api/v1/tools/signalwire-voice.json

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- [Bandwidth Voice API + MCP vs LiveKit Telephony](https://www.anchorterminal.com/compare/bandwidth-voice-vs-livekit-telephony.md)
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