DTMFmode for SIP client configuration

Syntax

 dtmfmode=inband  

Choices are inband, rfc2833, info or auto

• inband: The device that you press the key on will generate the DTMF tones. - If the codec is not ulaw or alaw then the DTMF tones will be distorted by the audio compression and will not be recognised. If the phone is set for RFC2833 and asterisk is set for inband then you may not hear anything.
• rfc2833: http://www.ietf.org/rfc/rfc2833.txt
• info: See SIP method info and SIP info DTMF or http://www.ietf.org/rfc/rfc2976.txt
• auto: Asterisk will use rfc2833 for DTMF relay by default but will switch to inband DTMF tones if the remote side does not indicate support of rfc2833 in SDP. This feature was added on Sep 6, 2005 and is not available in Asterisk 1.0.x.

Please note

Inband DTMF won't work unless the codec is ulaw or alaw (G711). Use out of band DTMF aka rfc2833 or info.

See also

• Asterisk DTMF
• Asterisk cmd SipDTMFmode: Change the DTMF type of an outbound SIP call
• SIP DTMF signalling
• Asterisk SIP channels