DTMF problems

DTMF digits are skipped

DTMF is handled by Asterisk. If some digits are missing or duplicated - that means that your Provider is not delivering DTMF codes correctly.

Possible steps to fix situation:

1. Enable debug mode in the Asterisk CLI to be informed of DTMF events
   1. In /etc/asterisk/logger.conf make sure you have such line at the end: console => notice,warning,error,dtmf
   2. In Asterisk CLI type: logger reload
2. Change DTMF type to RFC2833 (if it is other type)
3. In /etc/asterisk/sip.conf in [general] section set relaxdtmf=yes and rfc2833compensate=yes and reload Asterisk
4. Change Provider

Provider is not sending DTMF info

To check this:

• Enable dtmf log and sip debug log
• Make a call, check for such line

Non-codec capabilities (dtmf): us - 0x1 (telephone-event), peer - 0x0 (nothing), combined - 0x0 (nothing)

If you got this - that means provider is not delivering DTMF info in the SIP packet. Send him sip debug info and ask to fix this.

Correct line should look like this:

Non-codec capabilities (dtmf): us - 0x1 (telephone-event), peer - 0x1 (telephone-event), combined - 0x1 (telephone-event)

DTMF does not work with Asterisk 1.2

• In /etc/asterisk/sip.conf in [general] section set rfc2833compensate=yes and reload Asterisk

Source: http://lists.digium.com/pipermail/asterisk-commits/2006-August/006569.html

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See also:

• Asterisk DTMF
• http://irockasterisk.blogspot.com.es/2011/02/dtmf-issue-on-asterisk.html