Which vendors can actually run an assistant

GET 
/api/voice-agents/providers

The catalogue the assistant editor filters its vendor picker with, and it exists because the editor used to offer four vendors as equals while only ONE could produce a working assistant — the refusal arriving after the operator had filled in a form and pressed save.

Measured 2026-08-15 with a live POST: ElevenLabs and Cartesia realtime do not take the carrier's A-law wire (no_telephony_codec), and an AI leg only ever runs on that wire; Deepgram takes the wire but publishes no realtime model we have verified, and the store endpoint refuses every model value against an empty catalogue. Only OpenAI, on gpt-realtime-2.1, is creatable.

usable resolves the three conditions into the one answer the picker needs, computed on the server so the screen and the validator cannot drift into disagreeing.

Requires voice_agents.manage.

Responses

200

Every connectable vendor, with what it can and cannot do.

403

Authenticated but not allowed.