[Freeswitch-users] Question about srtp secured B-Leg

[Helmut Kuper]

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Hello,

I have late codec negotiation enabled and using Snom devices for
encrypted calls (inernal only). When sdp of A-leg (Snom) has a=crypto I
export sip_secure_media=true in my dialplan, so that B-leg (Snom) is
also encrypted via srtp. That works nicely.

When the B-Leg doesn't support srtp I got an "incompatible_device"
error. This is also ok so far.

Unfortunately this way you can't use Snom's optional srtp mechanism
which consists simply of two media profiles in A-Leg's SDP (first
RTP/SAVP then RTP/AVP) so the target can choose to encrypt or not.

I don't know whether this is RFC conform or not nor if this makes really
sense. I would like to be able to call a non encrypting ATA for checking
for eaxample fax devices by simply calling them.

My question is now, is there a way to tell FS sending outbound calls
also with a non crypto offer within same sdp to B-Leg, so that it can
choose to encrypt or not?


regards
helmut



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