Twilio vs Telnyx for Voice AI: Numbers, SIP and Real Call Testing
Compare Twilio and Telnyx by the telephone route you need, number ownership, call controls, complete costs and a practical acceptance checklist.
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Choose Twilio or Telnyx by the telephone path your application actually uses. Buying a number, streaming audio to an application and connecting a SIP trunk are related capabilities, but they have different setup, control and billing requirements.
If a voice agent works in a browser but fails when called from a phone, switching its language model is unlikely to explain the whole problem. First trace how the carrier connects the caller, where audio travels, and which service owns hangup and transfer behavior.
Provider documentation was checked September 25, 2026. This comparison does not contain a measured UK latency ranking or a claim that either carrier is universally cheaper.
Compare the appropriate connection type
| Requirement | What to verify with either carrier |
|---|---|
| Keep an existing number | Porting eligibility, paperwork, ownership, timing and a fallback plan |
| Use an application-controlled call | Incoming webhook configuration, authentication, answer and hangup events |
| Send audio to your application | Supported streaming direction, encoding, buffering and interruption controls |
| Connect a SIP voice platform | Trunk credentials or IP rules, inbound routing, outbound permissions and codecs |
| Transfer to a person | Exact transfer method, destination reachability, failure behavior and charges for all legs |
Twilio documents bidirectional audio through Media Streams. Telnyx documents its own bidirectional media-streaming interface. Those interfaces are not interchangeable, and neither should be confused with a SIP trunk configuration.
Start with the platform's supported route
A platform may integrate a carrier through SIP while another tutorial uses that carrier's WebSocket streaming API. Follow the route your platform documents. Copying configuration from the wrong architecture can leave the number connected to an endpoint that never serves the actual assistant.
LiveKit, for example, publishes Twilio SIP integration instructions. That documentation explains a connection pattern; it does not prove a particular Burki organization has completed the setup. Check carrier-specific readiness in your own workspace.
If you are evaluating Burki, inspect the telephony integration options and BYO SIP guide before purchasing another number. An existing carrier account may also have restrictions that application configuration cannot remove.
Make the recurring charges visible
Build a cost sheet with separate rows for number rental, inbound usage, outbound usage, the voice platform, AI providers, and optional features you enable. Ask how transfers and forwarded calls are charged. Record billing increments and destination-specific rates rather than assuming a single worldwide minute price.
A number may continue to incur rental while no customer is calling it. Pausing an assistant and releasing a carrier resource are different operations. Before removing a number, verify ownership, inbound traffic, outbound caller-ID dependencies, forwarding and SMS dependencies. Release only the resources you no longer need, then confirm the change in the carrier account.
Test the route from the caller's side
Use a phone number and destination you control. For each test, save the time, carrier call identifier and application call identifier so the records can be matched.
- Call inbound and confirm that both parties hear each other.
- Correct a detail while the assistant is speaking; check that old audio stops.
- End the call from each side and confirm resources are released.
- Exercise the actual human-transfer path, including a declined or unanswered destination.
- Compare the call duration and every charged leg with the carrier and platform records.
Repeat from the countries and networks that matter to your customers. A regional routing choice may influence results, but a benchmark must document its origin, destination, route, codec and timing definition before it supports a comparison.
Decide on operational fit
Keep the carrier that provides the required numbers and routes, understandable bills and a setup your team can support. Changing carriers can be worthwhile when a specific requirement fails; it is not a substitute for diagnosing one-way audio or incomplete transfer handling.
Before putting a real number into service, run the voice demo acceptance checklist. Check Burki pricing separately from your carrier bill so you know which company owns each charge.
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