Choose SIP and WebSocket diagnostics by the active transport

Identify what carries signaling and media

SIP is a telephony signaling protocol that can connect a carrier leg to a conversational service. A WebSocket media gateway instead handles a stream of audio frames and coordinates provider sessions in application code. These are transport choices, not interchangeable names for a voice model. Both can use the same owned public number while requiring different operator setup. Start an investigation with the call’s captured transport and media mode. Without that information, a healthy provider session in one path can be mistaken for evidence that the other path is available.

Keep the owned number and callback route stable

Lupin’s operator workflows preserve the Telnyx number and Call Control routing while validating the selected voice transport. The number’s identity should not change just because the media path changes. Record which deployment validated SIP and which validated the gateway, including configuration and test evidence. SIP passwords and API keys belong in private operator configuration and never in call responses or blog snippets. A transport activation requires provider readiness and authorization; successfully reading the phone resource is useful preparation but does not prove live audio is working.

Use transport-specific binding evidence

For signed post-call transcription, Lupin checks different ownership bindings according to the admitted transport. SIP metadata includes the configured provider phone identity and agent number, while the streaming path binds the saved media conversation and expects no mismatched phone metadata. Both also retain agent and peer checks. If a transcript fails binding, inspect the correct path rather than loosening validation. A transport migration that leaves stale metadata can otherwise attach content to the wrong session or make legitimate content unavailable, despite a valid provider signature.

Separate gateway framing from provider conversation health

The streaming gateway owns audio formatting, ordered frames, speech onset and cancellation for the cascade. Native audio can also run through the stored streaming transport while delegating audio behavior to the provider. That compatibility naming means scribe_ws does not always prove a standalone recognizer is active. SIP has its own connection and transfer observations. Check whether failure occurred during carrier setup, media authorization, provider socket preparation or conversation processing. A shared generic voice failed message is insufficient to choose the next safe diagnostic step.

Migrate one boundary at a time

To evaluate a transport change, retain the same number, peer allowlist, duration cap, workspace approvals and synthetic dialogue set. Compare call establishment, interruption recovery, transcript binding and confirmed hangup under each path. Preserve the earlier configuration for rollback and record any metrics that are no longer available. Do not assume that a working SIP deployment automatically activates streaming, or the reverse. The useful migration artifact is a transport-specific readiness record with explicit acceptance outcomes, allowing the operator to make an informed rollout without broadening account access or replacing phone identity.

Write transport-specific acceptance evidence

For SIP, retain the validated connection and transfer outcome. For the gateway, retain media authorization, frame handling and provider socket outcomes. Both records should include confirmed closure and transcript binding. The common public number connects the records operationally, while the separate acceptance evidence prevents one healthy path from concealing an untested alternative.

Sources & verification

Reviewed against current checked-in Lupin routes, shared contracts and official provider references. No live calls, OAuth authorizations, app actions or purchases were performed.

• Lupin phone, SMS and calls ↗Checked 2026-11-05
• Telnyx programmable voice events ↗Checked 2026-11-05
• ElevenLabs model reference ↗Checked 2026-11-05

Prepared with AI assistance by Lupin editorial. How we research and maintain these guides.