[SR-Users] Kamailio with Asterisk as Media Relay

[Daniel Tryba]

On Mon, Oct 08, 2018 at 07:16:43AM -0400, Alex Balashov wrote:
> The SDP-bearing INVITE and response are simply passed along as-is by
> Kamailio, and it is the SDP which specifies where the media goes. So, if
> endpoint A calls through Kamailio proxy B to Asterisk server C via SIP,
> A and C will negotiate media amongst themselves without any intervention
> or special measures on your part whatsoever.

In theory, but with Asterisk in the middle be prepared to have this fail
since it initially is in the loop regarding RTP and can negotiate
incompatible RTP legs between AB and BC which will not be fixed when
Asterisk leaves the RTP path. Mainly I experience this with
dtmf/telephone-events mapping, e.g.: a=rtpmap:101 telephone-event/8000
If a and c have different values, dtmf will fail.