I'm not sure this is posted anywhere, so I wanted to make sure it's here.
I have a carrier that sends both inband and RFC2833 DTMF.
For FreeSWITCH, this is fine, but if I bridge it on to someone else, then the remote system often processes both for duplicate DTMF.
Here's a local fix that works for me (but you can't be in bypass mode) to remove the inband (it always had rfc2833, but not always inband.)
Set this for the affected leg:
<action application="set" data="rtp_manual_rtp_bugs=FLUSH_JB_ON_DTMF"/>
<action application="set" data="jitterbuffer_msec=60"/>
<action application="set" data="sip_jitter_buffer_during_bridge=true"/>
I have in my notes: <action application="export" data="nolocal:drop_dtmf=true"/> but I don't see on the wiki that it's for sure that it works on inband, a quick look at the code and I still wasn't sure.
-Avi Marcus