API: Simba 1.6 is retired at version 2026-09-21 and served by current models from 2026-11-21

API: Simba 1.6 is retired at version `2026-09-21` and served by current models from 2026-11-21

simba-english and simba-multilingual - the Simba 1.6 pair - are being withdrawn in two steps:

From API version 2026-09-21 they are no longer selectable. Naming either returns 400 with the error code model_retired.
On 2026-11-21 both ids are served by our current models instead of their Simba 1.6 training. They keep answering on every API version that can still name them; what changes is the model behind the id, not your integration.

If you send	From 2026-11-21 it is served by
`simba-multilingual`	our current multilingual model, in every language you send it today
`simba-english`, English text	`simba-3.2`
`simba-english`, any other language	our current multilingual model

Nothing breaks on that date, but the audio changes. A voice you tuned on Simba 1.6 is rendered by a different model, and SSML <prosody pitch>, <prosody volume>, <emphasis> and <speechify:style emotion> are not applied by the current models, though breaks and <prosody rate> are. The request, the response, the voice IDs and the price stay the same.

To choose the model yourself, migrate before then - for most integrations that is a one-line change. Migrating off Simba 1.6 walks it step by step. Pinning your workspace’s API version to a date before 2026-09-21 keeps the Simba 1.6 training in the meantime with no code change at all.

Why the shorter notice. Our usual sunset window is 12 months. Simba 1.6 is a previous-generation family: it cannot serve /v1/audio/stream/with-timestamps at all and runs at roughly 2.5x the time-to-first-byte of the streaming-native models. Consolidating onto the Simba 3 fleet is what lets us keep improving latency and quality for everyone, and we did not want to spend a year running two stacks to do it.

Where to go if you migrate yourself.

From	To	Notes
`simba-english`	`simba-3.2`	English. Lower time-to-first-byte, richer expressivity, streaming-native. Serves every English voice in the catalog, your own cloned voices included.
`simba-english`	`simba-3.0`	English, and the API default. Pick it if you also need German, Spanish, French, Italian or Brazilian Portuguese. Accepts every catalog voice.
`simba-multilingual`	`simba-3.0`	English, `de-DE`, `es-ES`, `es-MX`, `fr-FR`, `it-IT`, `pt-BR`. Streaming-native, and a cloned voice speaks all of them from one voice ID.

An omitted model is unaffected: it already resolves to simba-3.0.

If you synthesize outside Simba 3.0’s seven locales, simba-3.0 on its own is not a like-for-like replacement, and we are not asking you to drop those languages. Broader multilingual coverage on the current model generation is what serves simba-multilingual from 2026-11-21, and it reaches the full set the pair covers today. Talk to us if you want to test it before the date.

What changed at this version. POST /v1/audio/speech and both /v1/audio/stream routes reject the two ids. GET /v1/audio/models returns only the models you can actually call, and each voice’s models array in GET /v1/voices does the same - so a picker driven off either endpoint stays correct without special-casing.

Read the dates off the API. While your workspace is pinned below 2026-09-21, both models still appear in GET /v1/audio/models carrying retired_at: "2026-09-21" and sunset_at: "2026-11-21". sunset_at is the day the model behind the id changes; surface it in your own tooling if you have a deadline to track.

See the API Versioning guide for how to read and set your workspace’s pinned version.