Outbound DTMF Method Override

Parameter group

VoIP DTEA and DTNA Media


DTNA only

Access level


Possible values

Use negotiated values
DTMF using tones (‘in-band’ audio tones in the RTP stream)
DTMF using payload (RFC2833 payload)
DTMF using SIP info (using the SIP INFO method)


Use negotiated values (what is agreed as part of the SIP protocol)


Normally, the DTMF method is limited to RTP methods only (in-band/payload). However, using the System Parameter Outbound DTMF Method Override, it is possible to force the DTMF transmission type to be in-band, payload or (the new option) SIP Info method. In this case, any State Table ‘Dial’ action will cause DTMF keys to be sent using the SIP INFO method. If you want the DTMF transfer method to be agreed as part of the SIP call setup process (by the SDP in the INVITE and 200 OK messages), set this option to Use Negotiated Values. See also Inbound DTMF Method Override.