VAPI•4mo ago

DTMF failing for IVR for some systems

We’re using Twilio numbers and are seeing cases where DTMF consistently fails to navigate IVR for some select systems. When we call the number ourselves on our phones, we can navigate the IVR without problems.

We're using the

dtmf

dtmf

dtmf

dtmf tool as instructed in the docs https://docs.vapi.ai/tools/default-tools#dial-keypad-dtmf

Is there anything else we can set to get DTMF working more reliably?

Default Tools | Vapi

Adding Transfer Call, End Call, Dial Keypad, and API Request capabilities to your assistants.

KyleAPP•9/9/25, 2:21 PM

Hi RiceFT,

For ensuring the reliability of DTMF inputs when using Twilio numbers to navigate IVR systems, consider the following recommendations from our IVR Navigation Guide:

Add Short Pauses Between Digits: IVR systems can require slower input to accurately recognize tones. Use the pause character ww for a 0.5s pause or WW for a 1s pause in your DTMF sequences. Start with 0.5s pauses and adjust if necessary. For instance, use 1w2w3#1w2w3# instead of 123#123#.
Wait for Menu Completion: Ensure your assistant waits for all menu options to be spoken before sending DTMF tones. This can be achieved by having it reply with a single space character (" ") to stay silent while waiting.
Retry with Slower Inputs or Spoken Commands: In case of missed inputs, retry with progressively slower gaps between digits. If this continues to fail, consider using spoken input as a fallback.
Compare Telephony Providers: If issues persist, and recognizing that DTMF reliability can vary across providers, test with different telephony transport methods available through Twilio or other providers if practical for your setup.

Implementing these strategies should enhance the reliability of DTMF navigation in your scenario.

DTMF failing for IVR for some systems

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