Configure inband DTMF for X-Lite29 Dec 2007
X-Lite can send 3 different types of DTMF, and you need to know which to use or to try all methods:
This is the most likely solution:
Dial ***7469 (send)
Once you get the advanced options menu up, filter first for DTMF. Find the Force Inband DTMF entry, and change the value accordingly.
Then filter for 2833. Find the RTP 2833 enabled line, and change this value accordingly.
Setting both to 0 will force DTMF as SIP_INFO