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A custom language-model endpoint answers model requests. It does not receive telephone audio or supply a Twilio media bridge.
Threetone supports a dashboard connection probe for a custom model candidate. Custom-model publication is currently rejected, and Twilio calling has separate runtime requirements. A successful model probe does not release either path.

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Prepare the integration design

Collect the model base URL and model ID, credential reference, desired phone route, and an owner for each service. Use custom models for the supported probe and draft workflow.
1

Check the model contract

Review endpoint compatibility, including streaming responses and tool behavior. Record probe failures separately from any telephony findings.
2

Choose the media boundary

Decide whether the future runtime will receive SIP media or implement a provider-specific streaming bridge. Do not point a Twilio stream at a Chat Completions endpoint.
3

Specify the conversation lifecycle

Document how the bridge will handle audio conversion, transcription, synthesized speech, interruptions, silence, and caller hangup. Define the result when the model times out or the media connection closes.
4

Keep release checks independent

Require an executable custom-model version, supported credential delivery, a released media adapter, and the phone route’s acceptance evidence before moving traffic.
Twilio distinguishes receive-only Media Streams from bidirectional streams. The latter uses Connect with Stream and blocks subsequent TwiML until the connection disconnects. Those provider capabilities do not establish a Threetone WebSocket endpoint. See Twilio Media Streams.

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Failure handling

Plan a bounded model timeout and a caller-facing fallback. Keep provider call IDs, model request IDs, and your application correlation ID separate so a model error is not misreported as a carrier failure. Do not retain audio or transcripts without a reviewed purpose and retention policy.

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Frequently asked questions

No. Current publication rejects custom model execution. Preserve the reviewed candidate as a draft.
No. Twilio’s unidirectional stream cannot play application audio back. A supported bidirectional integration would need a separate media implementation.