Hi
I have 2 softphones PhonerLite (they support
SRTP via SDES ) and the freeswitch (windows RC1 version) server and I wanted to
make secure call between those two endpoints (SRTP).
I spend whole day on
testing this scenario and my conclusions are:
- when the option: <action
application="export" data="sip_secure_media=true"/> is uncommented, and both
enpoints have enabled SRTP then:
1) Initiator of the session sends SIP Invite
with a=crypto paramter and supported codecs
2) Freeswitch receives SIP Invite
and sends SIP Invite to the receiver (also with the crypto)
3) Receiver
receives the SIP Invite with the a=crypto parameter and he sends back supported
codecs with 200 OK message (but without a=crypto parametr. Is that ok? I'm
afraid not)
4) Freeswitch sends 200 OK message but witout any codecs: m=audio
0 RTP/AVP 19 and no a= parameters!
5) Final result is that the second leg of
the session between Freeswitch and receiver has SRTP transport enbaled and the
first leg (initiator- Freeswitch) doesn't hear anything - no codecs! However
Freeswitch is sending RTP (not SRTP) pacekets to the initiator.
Could someone explain to me, what is going on, and
why freeswitch doesn't forward codecs accepted by the receiver to the
initiator?
Is it a PhonerLite's bug or freeswitch's? Maybe someone has tested
SRTP with the PhonerLite softphone or any other free softphone with srtp
support?
When I uncommented: <param
name="Inbound-no-media" value="true">
everything works fine. The parameter
<action application="export" data="sip_secure_media=true"/> doesn't change
anything then (but i cound miss something).
Thanks for help
Chris