DTMF - Dual-Tone Multi-Frequency signaling
This signaling method is used for telecommunication over analogue telephone lines in the voice-frequency band between telephone handsets and other communication devices and the switching center.
There are 3 methods of sending DTMF in the SIP environment:
Flashphoner supports DTMF with 1 and 2.
To send DTMF using SIP INFO packets, the following parameter in flashphoner.properties file should be set
dtmf=INFO |
To receive DTMF using SIP INFO packets, PBX should be configured as follows (Asterisk for example)
[general] bindport=5060 bindaddr=0.0.0.0 context=default dtmfmode=info allow=all [2000] type=friend secret=2000 host=dynamic canreinvite=no dtmfmode=info |
Note that Asterisk uses inband
method by default which does not supported by WCS.
To send DTMF as specially marked events according to RFC 2833, the following parameter in flashphoner.properties file should be set
dtmf=RFC2833 |
Also, telephone-event
codec should be enabled, for example
codecs =opus,alaw,ulaw,g729,speex16,g722,mpeg4-generic,telephone-event,h264,vp8,flv,mpv codecs_exclude_sip =mpeg4-generic,flv,mpv,alaw,ulaw,g729,speex16,g722,vp8 codecs_exclude_streaming =telephone-event codecs_exclude_sip_rtmp =opus,g729,g722,mpeg4-generic,vp8,mpv |
In the case above, H264
for video, opus
for audio and telephone-event
for DTMF are enabled.
To receive DTMF according to RFC 2833, PBX should be configured as follows (Asterisk for example)
[general] bindport=5060 bindaddr=0.0.0.0 context=default dtmfmode=rfc2833 allow=all [2000] type=friend secret=2000 host=dynamic canreinvite=no dtmfmode=rfc2833 |
Note that Asterisk uses inband
method by default which does not supported by WCS.