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What is Cartesia used for in a Bolna voice agent?
Cartesia is the text-to-speech provider that turns your Bolna agent's replies into speech using its Sonic models, which cover 42 languages and respond fast enough for live phone calls. Pick it when time-to-first-audio matters most: Bolna's provider guide lists Cartesia as the lowest-latency option for English.
How do I set up Cartesia with Bolna?
- Optional: connect your own Cartesia API key at platform.bolna.ai/auth/cartesia. You can also use Bolna's bundled access.
- Open your agent in Agent Studio and go to the Languages tab (previously called Audio).
- Pick the language you are configuring, then in the Voice section choose Cartesia as the provider.
- Select a model (
sonic-3.5is recommended for production) and pick a voice. Use the play button to preview it with your welcome message. - Place a test call. To use your own voice, click Add new voice in the voice list and clone it with Cartesia as the provider.
For every setting, see the Cartesia setup guide in the Bolna docs.
Which Cartesia models and languages does Bolna support?
| Model | What it is | Languages |
|---|---|---|
sonic-3 | Stable Sonic 3 release | 42, including Hindi |
sonic-3.5 | Stable Sonic 3.5 release, recommended for production | 42, including Hindi |
sonic-3.6 | Sonic 3.6, the newest Sonic model | 42, including Hindi |
All three models work with every Cartesia voice available in Bolna. When you create an agent through the API, language is required in the Cartesia synthesizer config.
What can you build with Cartesia and Bolna?
Fast-paced support lines. Short, quick replies keep busy inbound queues moving without long pauses between turns.
English and Hindi agents in one flow. Use Cartesia for English and another provider per language in a multilingual agent. The Bolna docs give the example of Deepgram transcription with Cartesia for English.
Branded custom voices. Clone a voice from a clean 1 to 2 minute recording and use it across every agent in your workspace.
Sales and appointment calls. Outbound qualification and reminder calls where a quick, natural reply keeps the caller on the line.