[Freeswitch-users] ZRTP call setup

[Ben ben_naylor1942@hotmail.com]

Hi Freeswitch community!

Could someone advise on how you have the a-leg as a non-ZRTP client, and
the b-leg as a ZRTP client, with trusted main-in-the-middle?

I have set up trusted man-in-the-middle with the server, which works well
when making an outbound call from the ZRTP client to the standard SIP
client.  The INVITE from the ZRTP client includes the zrtp hash in the SDP
info, which I'm presuming highlights to freeswitch that the call will be
using ZRTP for this leg.  The Freeswitch then decrypts the ZRTP ready for
the b-leg.  Everyone's happy.

However, when going the other way, the INVITE from the non-ZRTP device does
not include zrtp hash.  So the INVITE passed to the ZRTP client does not
include a ZRTP hash, which then causes the ZRTP client to fail.  I have
tried getting around this by adding the following in the dialplan -

<action application="set" data="zrtp_secure_media=true"/>

But the freeswitch doesn't create the zrtp hash in the INVITE.

Is there something I can do in Freeswitch to say "all calls to this phone
must use ZRTP (hash), whether the original INVITE uses ZRTP or not"?

Thanks in advance for the help!
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