VICIdial Error: DTMF Not Working — Cause & Fix

Error Summary

Error Message

DTMF Not Working

Severity

Warning

Component

Asterisk

What Causes This Error

DTMF tones (keypad presses) are not being detected or transmitted correctly. Agents pressing keys during IVR navigation or transfer scenarios have no effect. Caused by DTMF mode mismatch between VICIdial/Asterisk and the carrier (RFC2833 vs. SIP INFO vs. in-band), codec transcoding issues (G.729 drops DTMF), or NAT issues with RTP DTMF packets.

How to Fix It

  1. 1
    Check current DTMF mode in sip.conf: grep dtmfmode /etc/asterisk/sip.conf
  2. 2
    Set to RFC2833 (most compatible with carriers): dtmfmode=rfc2833
  3. 3
    If using G.729, switch to ulaw/alaw to preserve in-band DTMF
  4. 4
    Check carrier DTMF requirements (contact carrier support)
  5. 5
    Test DTMF detection: dial into test IVR and verify key presses register
  6. 6
    Enable DTMF debug: asterisk -rx 'core set verbose 5' then press keys in active call
  7. 7
    If using SIP INFO: dtmfmode=info in sip.conf for that peer

How to Prevent It

Document DTMF mode requirements for each carrier and configure correctly at setup. Test DTMF during initial carrier integration. Avoid G.729 codec if DTMF relay is needed for IVR interaction.

Critical SIP Registration Failed Asterisk Warning Transfer Failed Asterisk Critical Audio One Way Network

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Frequently Asked Questions

What causes the VICIdial "DTMF Not Working" error?
DTMF tones (keypad presses) are not being detected or transmitted correctly. Agents pressing keys during IVR navigation or transfer scenarios have no effect. Caused by DTMF mode mismatch between VICIdial/Asterisk and the carrier (RFC2833 vs. SIP INFO vs. in-band), codec transcoding issues (G.729 drops DTMF), or NAT issues with RTP DTMF packets.
How do I fix the VICIdial "DTMF Not Working" error?
Check current DTMF mode in sip.conf: grep dtmfmode /etc/asterisk/sip.conf Then: Set to RFC2833 (most compatible with carriers): dtmfmode=rfc2833 Then: If using G.729, switch to ulaw/alaw to preserve in-band DTMF Then: Check carrier DTMF requirements (contact carrier support) Then: Test DTMF detection: dial into test IVR and verify key presses register Then: Enable DTMF debug: asterisk -rx 'core set verbose 5' then press keys in active call Then: If using SIP INFO: dtmfmode=info in sip.conf for that peer
How can I prevent the "DTMF Not Working" error in VICIdial?
Document DTMF mode requirements for each carrier and configure correctly at setup. Test DTMF during initial carrier integration. Avoid G.729 codec if DTMF relay is needed for IVR interaction.