other-emerald•3d ago

How can I override assistant voice when receiving inbound calls?

Here is the output I return:

{"assistantId":"ASSISTANT_ID","phoneNumberId":"PHONE_NUMBER_ID","assistantOverrides":{"variableValues":{"firstName":"George"},"voice":{"provider":"vapi","voiceId":"hana"}}}

It doesn't change any of the settings.

5 Replies

Vapi Support Bot•3d ago

To override the assistant voice for inbound calls, try using a supported provider like "azure" in your assistantOverrides. For example:

"assistantOverrides": {
  "voice": {
    "cachingEnabled": true,
    "provider": "azure",
    "voiceId": "andrew"
  }
}

"assistantOverrides": {
  "voice": {
    "cachingEnabled": true,
    "provider": "azure",
    "voiceId": "andrew"
  }
}

Make sure the provider and voiceId are valid and supported for your account, as using "vapi" may not work for this override according to the documentation I have found. See the API reference for more details: Vapi API Reference. Source: - Vapi API Reference: Create Phone Call

⤵️ Mention @Vapi Support Bot for follow-ups 🐥

other-emeraldOP•2d ago

Is there any chance I can override the voice with Vapi voice? The API Reference clearly offers different voice providers including Vapi. My endpoint successfully receives the reuqest but the output overrides are not being applied. How can this be fixed?

sensitive-blue•2d ago

I can help you get the Vapi voice overrides working correctly. It looks like your request reaches the endpoint, but assistantOverrides aren’t being applied. Often, this happens if the request is sent before a conversation starts or in the wrong context. Can you confirm whether you’re sending this during an active conversation or as a pre-call setup? Once we clarify, I can assist you on the correct request structure so the voice changes actually take effect. @Aram Vardanyan

other-emeraldOP•2d ago

Actually, I'm new to Vapi and didn't know how to handle pre-call setups so it can maintain the assistant config and override the voice only. Now, I just removed the attached assistant from the phone number and it worked. Seems the problem was that overriding was disabled if there is an assistant attached. However, I'd like to know what the best practices are for reducing the latency since it's too high. What do you recommand?

sensitive-blue•13h ago

I’m glad you got the override issue sorted — that makes perfect sense when an assistant is attached to the phone number. High latency usually comes from a mix of model size, TTS rendering speed, and how your pre-call/webhook logic is structured. I can help you review your setup and optimize things like model choice, streaming, server response times, and Vapi fast-start patterns. With the right configuration, we can cut your latency down significantly and smooth out the call experience. If you’d like, we can go over the details privately so I can assist you @Aram Vardanyan ?

How can I override assistant voice when receiving inbound calls?

Did you find this page helpful?