[Freeswitch-users] How can I trigger a ZRTP connection on an existing call?

[Peter Steinbach]

Hello Brian,

thanks for the hint. In the meantime, I tried both, setting zrtp
globally in Freeswitch and having zrtp in the original dialplan and in
the {}-Variables for dialing the B party. This did not help.

Then I totally disabled ZRTP inside FSs and in the dialplans and grepped
on the network. Then I issued a "uuid_media off" for starting a reinvite
between the 2 endpoints. On the Freeswitch console, I could see, that
ZRTP is exchanged in the SDP, although Freeswitch does a reinvite with ZRTP.
Having a look at the channel variables, I could see that

  * variable_rtp_local_sdp_str does _not_ contain ZRTP
  * variable_switch_m_sdp _does_ contain ZRTP
  * variable_switch_r_sdp _does_ contain ZRTP

But ZRTP however is not started on both sides. Then I killed Freeswitch
during a call and started again, the calls were automatically recovered,
and ZRTP was there. But this was surely done with a normal invite, right?

I tried with CsipSimple on Android and Jitsi nightly on Ubuntu. Both
clients behave the same. I assume, that they will not start ZRTP on a
reinvite.

So unless there is now way to reistablish a call (I tried uuid_transfer
to the same number with autoanswer, but target number was still
considered as busy), I think it will not work.

Any other hints?

Best regards
Peter



On 02/10/15 16:05, Brian West wrote:
> You can't set the zrtp_secure_media=true after a session is created,
> it needs to be a global or you set it inside the {} on the bridge or
> originate line.    Then you're outlining uuid_media off, which would
> make the media go between the two endpoints, FreeSWITCH isn't even
> involved in the zrtp exchange at that point.  Technically your
> endpoints should be the ones doing this and ZRTP should be disabled in
> FreeSWITCH, You really only need ZRTP with MiTM if you MUSt transcode
> or you're terminating directly on the FreeSWITCH instance.   I should
> really just rip out MiTM support.
>
> On Tue, Feb 10, 2015 at 5:53 AM, Peter Steinbach <lists at telefaks.de
> <mailto:lists at telefaks.de>> wrote:
>
>     Hello,
>
>     I want to establish ZRTP, after I am bridging 2 calls, which have
>     been active already before.
>
>     My scenario is as follows:
>
>       * Caller A is calling Freeswitch, the call is answered and an
>         announcement is played
>       * In the meantime Freeswitch calls another Party B and connects
>         it to an internal IVR, where also announcements are played.
>       * Now, after a while, I decide to connect the calls together,
>         then send an "uuid_media off <uuid>" to the calling party A
>         leg, reinvites occur and bypass media works.
>       * However the 2 SIP clients (Csipsimple) do not start a ZRTP session
>       * If caller A calls B directly via bypass media, the ZRTP is
>         active, by the way.
>
>     I suspect that ZRTP somehow should be forced or triggered. Is
>     there a way to do that? I already invited the B leg with
>     "zrtp_secure_media=true" and issued
>
>       uuid_setvar 1bd508af-19c7-4e38-8621-731baaf33920
>     zrtp_secure_media true
>       uuid_media off 1bd508af-19c7-4e38-8621-731baaf33920
>     to the A leg. But this did not work.
>
>     The main question should be: How can I trigger a ZRTP connection
>     on an existing call?
>
>
>     -- 
>     With kind regards
>     Peter Steinbach 
>
>     Telefaks Services GmbH
>     mailto:lists (att) telefaks.de <http://telefaks.de>
>     Internet: www.telefaks.de <http://www.telefaks.de>
>
>
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>
> */Brian West/*
> brian at freeswitch.org <mailto:brian at freeswitch.org>
>
>
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-- 
With kind regards
Peter Steinbach 

Telefaks Services GmbH
mailto:lists (att) telefaks.de
Internet: www.telefaks.de

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