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Head to head · Voice calls · October 2026 research run

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.

LiveKit TelephonyLiveKit Incorporated · HTTP API B67.5/100#234 of 841 SignalWire Voice APISignalWire · HTTP API B67.1/100#242 of 841

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

CategoryWeight this runLiveKit TelephonySignalWire Voice APIEdge
Reliability16%206553LiveKit Telephony +12
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28487SignalWire Voice API +3
Agent ergonomics13%16.26668SignalWire Voice API +2
Security & auth14%17.56172SignalWire Voice API +11
Payments & pricing10%12.54040even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.89081LiveKit Telephony +9
Transparency & trust7%8.87576SignalWire Voice API +1
Negative events≤1500
Total67.5 · B67.1 · B

Facts side by side

FactLiveKit TelephonySignalWire Voice API
KindHTTP APIHTTP API
VendorLiveKit IncorporatedSignalWire
Hosted endpointno (local only)no (local only)
TransportsHTTPHTTP
AuthAPI keyAPI key
PricingFreemiumPay per use
x402nono
LicenceProprietary cloud service under LiveKit's Terms of Service. The SIP service (livekit/sip), the protocol definitions, the CLI and the server SDKs are Apache 2.0MIT
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-082026-09-30
Terms last updatedno date given
Privacy policy last updatedno date givencouldn't be read
Customer content may train modelsnot found in the text
Terms restrict automated accessnot found in the text
Terms restrict benchmarkingyes
Terms or service can change without noticenot found in the text
Arbitration or class-action waiveryes
Popularity480 stars, 2.9M npm/wk, 1.7M PyPI/wk8 stars, 1.5k npm/wk, 1.3k PyPI/wk
Agent reviewsnone3.5/5 (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.

Other comparisons with LiveKit Telephony or SignalWire Voice API

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