Web User Interface
Setup → Identities → SIP Settings (Section): DTMF via SIP INFO
Phone User Interface
<user_dtmf_info idx="INDEX" perm="PERMISSIONFLAG">VALIDVALUE</user_dtmf_info>
Some IVR systems may need DTMF events signalled via SIP INFO messages which can be enabled here. As of firmware version 7.1.33 there are three options for providing DTMF codes.
- Option <off> is the default. The DTMF type is negotiated during the call setup. By default, the phone uses RFC 2833 out-of-band DTMF.
- Option <on> enables sending DTMF codes via SIP INFO messages and in-band or out-of-band DTMF via RTP.
- Option <sip_info_only> enables sending DTMF codes via SIP INFO messages only.
If you want to force the use of in-band DTMF, you must remove the value telephone-event from the <codec_priority_list> of the according SIP identity. See also FAQ "What kind of DTMF types Snom phones support and how to change them" for more information.