The code needs to be updated to be able to catch `a=rtcp-fb:`, probably it was not a common attribute when the sdp parser was written and not covered at that time (iirc, it was @ovidiusas writing the sdp parser).
The solution right now is to use `subst_body()` function to remove lines from sdp matching `a=rtcp-fb:ID`, replacing the ID with the corresponding codec numeric ids:
* https://www.kamailio.org/docs/modules/stable/modules/textops.html#textops.f....
If you do not want video media stream, there is a function to remove it all together:
* https://www.kamailio.org/docs/modules/stable/modules/sdpops.html#sdpops.f.sd...