Bland AI

Bland AI generates speech from a voice id, which also selects the Bland model (for example btts-3). Bland tuning is passed in synthesizer.options.

{
  "verb": "say",
  "text": "Hi there, your order ships today.",
  "synthesizer": {
    "vendor": "bland",
    "language": "en-US",
    "voice": "29158307-9893-4149-8a75-bc9ce313d64e",
    "options": {
      "expressiveness": 0.7,
      "stability": 0.5
    }
  }
}

You can also set these in the portal under Extra Options on the speech credential, in which case they apply to every request that uses that credential. Settings supplied on the verb take precedence.

Credential

Create an API key in your Bland account. jambonz sends the key as Authorization: Bearer <api key>. Add it as a Bland AI speech credential in the portal or API, using the vendor id bland. Bland AI is used for text-to-speech only.

Voices and languages

A voice is a Bland voice UUID; voice names are not accepted. The voice decides the model, so there is no model setting. The portal lists these built-in voices under English (US):

Cloned voices and voices added from the Bland library work when you enter their UUID as a custom voice.

Bland has no language parameter, so synthesizer.language is not sent to Bland; the voice determines how the text is spoken.

jambonz asks Bland for 16-bit PCM at 16 kHz and resamples it to the call’s rate.

Options

Every option is optional. An option you don’t set is not sent, so the voice’s own default applies.

Endpoint override

To point at a non-default endpoint, such as a proxy, set the API base URL on the credential, or api_uri in its Extra Options. Leave it out to use api.bland.ai.

Streaming

Bland AI supports TTS streaming, so it can be driven token by token from an LLM using tts:tokens, for example from the agent verb. jambonz streams text to Bland over a live connection and starts a new Bland context for each turn; on barge-in it cancels the current context and drops its remaining audio instead of reconnecting.

Bland does not return word-level timestamps, so alignment events are not available.

Bland accounts have a concurrency limit. A live streaming connection counts against it, so a second call or a non-streaming say on the same account can be rejected with concurrency_limit_reached until the first one ends.