Cartesia Sonic 2 and Turbo stop October 20: Sume model ids

Cartesia's older-models page says sonic-2 (every sonic-2-* snapshot) and sonic-turbo stop working on October 20, 2026, and that the sonic-3-2025-10-27 snapshot sunsets the same day. Cartesia names Sonic 3.6 as the replacement. Sume's TTS Router does not list sonic-2 or sonic-turbo; its model values are sonic-3.6, sonic-3.5, sonic-3, sonic-latest and sonic-preview.

Cartesia facts are from its docs, read 2026-10-01. Sume facts are from the TTS Router in the Sume API reference and its catalog code. If you call Cartesia directly with a retiring id, change it before the date; on Sume there is nothing to migrate for these two ids.

What exactly stops working on October 20?

Three things, per Cartesia's page. Cartesia also lists the ids that stay active.

Which Sume model id replaces each one?

Sume's router uses family ids with no dates. There is no sonic-2 or sonic-turbo row in its catalog, so the only change a retiring id needs is a move to a Sonic 3 id. A dated snapshot such as sonic-3-2025-10-27 cannot be pinned on Sume at all, because the model enum has no dated values.

How do I call Sonic 3.6 on Sume?

POST /v1/tts-router/generate takes a model, a transcript and a voice. The result is a job; the audio is a Sume-hosted file when it completes. For non-English scripts add a language.

curl -X POST https://api.sume.com/v1/tts-router/generate \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: sonic-migrate-001" \
  -d '{
    "model": "sonic-3.6",
    "transcript": "Your order ships tomorrow.",
    "avatar_handle": "my-avatar",
    "language": "en"
  }'

What does the move cost and limit?

The router charges on the same character book as TTS 1.0: $0.0475 per 1,000 characters, plus a 5.5% agent fee by default. The request schema caps transcript at 20,000 characters. sonic-preview is a beta channel and fails with voice_model_mismatch for pro voice clones, so keep it out of production. See Cartesia Sonic 3.6 API ids for the full id table.