MAI custom voice SSML (ttsembedding) vs Sume voice ids: what is gated
Microsoft's MAI-Voice-2.1 custom voice sits behind Limited Access Review and uses a speakerProfileId in SSML. Sume picks voices by id, with no clone widget.
To use a custom MAI-Voice-2.1 voice you need Microsoft's Limited Access Review approval, then reference a speaker profile in SSML with a ttsembedding element. Sume TTS selects voices by id and its MCP tool says there is no voice-cloning or voice-upload widget.
How Microsoft's flow works
Per the Learn page: a reference clip of 5 to 60 seconds, consent audio and a prompt are uploaded, and the SSML names the base model and the profile (<voice name='MAI-Voice-2.1'> wrapping <mstts:ttsembedding speakerProfileId='...'>). Access is gated, so plan lead time.
| Step | MAI-Voice-2.1 | Sume TTS 1.0 |
|---|---|---|
| Access | Limited Access Review | None for voice selection |
| Voice reference | speakerProfileId in SSML | voice.id (UUID or voi_ + 32 hex) |
| Clone from a clip | Yes, 5 to 60 s reference | No widget in the TTS tool |
| Markup | SSML | No SSML |
What Sume does instead
Sume validates voice.id (a bad value returns 400 invalid_voice_id) or takes an avatar voice marked ready. Voices are created through the voices tooling rather than by uploading a sample inside the TTS call (API reference).
If your brief requires the voice of a specific real person, Sume's TTS endpoint is not the path, and we are not claiming it is. Get consent and use a vendor flow built for it.
Pricing context
Microsoft lists $22 per million characters for standard and $15 for Flash; whether custom voices use the same rate is not stated on the pages we read.
Sources
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