VAPI•3mo ago

SSML Not Working with ElevenLabs Custom Voice Despite enableSsmlParsing Enabled

Description:

I'm experiencing issues with SSML parsing not being respected when using a ElevenLabs voice, despite having successfully enabled enableSsmlParsing: true via PATCH request.

Configuration:

Assistant ID: 844995ac-4928-45b1-a262-3fd634b88658

Voice Provider: ElevenLabs (11labs)

Voice: "Raquel pro v1"

Model: eleven_multilingual_v2

SSML Parsing: Enabled via PATCH to /assistant/{id} endpoint (confirmed with GET request showing enableSsmlParsing: true)

Issue:
SSML tags like <break time="1.5s"/> and <speak></speak> are being completely ignored. The assistant reads through text without any pauses, making it impossible to control pacing when reading lists of available appointment times.

What I've Tried:

Successfully enabled enableSsmlParsing via PATCH request (200 OK response)

Verified setting with GET request - shows enableSsmlParsing: true in voice config

Tested with both single quotes <break time='1.5s'/> and double quotes <break time="1.5s"/>

Ensured SSML is wrapped in <speak></speak> tags

Verified webhook is sending correct SSML string to VAPI

Tested with different break times (500ms, 1s, 5s) - none work

Expected Behavior:
SSML tags should be processed and pauses should occur when specified, allowing control over speech pacing and rhythm.

Actual Behavior:
All SSML tags are ignored. The voice reads continuously without any pauses, making the output sound rushed and unnatural when listing multiple items.

Vapi Support BotAPP•10/9/25, 10:58 AM

Suggestion:
Based on the documentation, SSML and advanced pronunciation features are only fully supported on specific ElevenLabs models like eleven_turbo_v2eleven_turbo_v2 and eleven_flash_v2eleven_flash_v2, not necessarily on eleven_multilingual_v2eleven_multilingual_v2. Try switching your assistant's model to eleven_turbo_v2eleven_turbo_v2 in your voice configuration and test SSML parsing again:

{
  "voice": {
    "model": "eleven_turbo_v2",
    "voiceId": "your-voice-id",
    "provider": "11labs",
    "enableSsmlParsing": true
  }
}

{
  "voice": {
    "model": "eleven_turbo_v2",
    "voiceId": "your-voice-id",
    "provider": "11labs",
    "enableSsmlParsing": true
  }
}

If SSML works after this change, the issue is likely due to model compatibility.

Source:

Pronunciation dictionaries documentation

⤵️ Mention @Vapi Support Bot for follow-ups 🐥

forward-apricotOP•10/9/25, 11:09 AM

I have jus tried with eleven_multilingual_v2 model voice and no way

KyleAPP•11/3/25, 11:34 PM

We apologize for the delay in responses lately. We are in process of making some changes to our workflow in how we handle support requests. The good news is that we are starting to get back on track of having a 48 hour response time and we would like to start cleaning up anything old.

With that being said, just wanted to check in with you to see if you have made any progress or changes to your project since support has last reached out.

forward-apricotOP•11/5/25, 4:32 PM

there haven't been any

KyleAPP•11/18/25, 4:28 AM

I sincerely apologize for the delayed response to your support request.
We implemented better tracking for support tickets to ensure timely responses going forward, but due to a technical limitation, this only applies to tickets created after this past week.
I'm closing this older ticket, but if your issue still needs attention, please:
Reply with 'REOPEN' or
Email support@vapi.ai with any updates
I'll personally ensure your new request gets prompt attention.
Thank you for your patience.
Best regards,
Vapi Support Team

SSML Not Working with ElevenLabs Custom Voice Despite enableSsmlParsing Enabled

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