[SR-Users] Re-invites from carrier breaks the call

Andres andres at telesip.net
Thu Feb 19 18:59:46 CET 2015


On 2/18/15 9:44 PM, Will Ferrer wrote:
> Hi Alex
>
> Thanks so much for the reply.
>
> Is there anything that we could do perhaps that is a more creative 
> solution, for instance not passing the re-invite all the way to the 
> softphone and just responding from the kamailio box handling the call?
>
> We tried this as well actually, but we didn't get it to work. We just 
> sent a 200 ok from the kamailio box, no sdp or anything on the packet 
> since we sent it with just send_reply and the carrier just sent a bye.
>
> Hopefully there is something clever we could do to correct the 
> problem, it is preventing us from using alot of our carriers since the 
> re-invite breaks our clients softphones.
>
> Thanks again for the assistance.
We have struggled with this issue ourselves.  The problem was that we 
did not want our SIP server to behave like an open relay.  We were 
seeing that the session-timer Re-Invites have a  Request-URI with the IP 
of the other
endpoint instead of the Proxy.  If the SIP server is an open relay then 
no problem, but ours is not so the config file was very strict and 
dropped the Re-Invite (since the Request-URI had an external IP) thus 
dropping the call.  The config file could be enhanced by testing for 
has_totag() since the Re-Invite has the totag but an original Invite 
does not, but the hacker could put a bogus totag and make calls so its 
more secure to leave it this way.  We ended up disabling session-timers 
at some our clients PBXs.  Its always a balancing act between 
convenience/services and more security.  We chose more security.
>
> All the best.
>
> Will Ferrer
>
> On Wed, Feb 18, 2015 at 6:07 PM, Alex Balashov 
> <abalashov at evaristesys.com <mailto:abalashov at evaristesys.com>> wrote:
>
>     Kamailio cannot correct this. This is an endpoint issue. The whole
>     point of Record-Route is to hairpin sequential requests (and
>     indeed, their replies) through the proxy. The endpoints need to
>     comply by affixing the correct Route header to the end-to-end ACK.
>
>     --
>     Sent from my BlackBerry. Please excuse errors and brevity.
>     *From: *Will Ferrer
>     *Sent: *Wednesday, February 18, 2015 9:01 PM
>     *To: *Kamailio (SER) - Users Mailing List
>     *Reply To: *Kamailio (SER) - Users Mailing List
>     *Subject: *[SR-Users] Re-invites from carrier breaks the call
>
>
>     Hi All
>
>     We have any issue with re invites coming from the carrier.
>
>     When a reinvite occurs, our softphone client gets the invite,
>     sends a 100, and then sends 200 ok. However the 200 ok does not
>     have the softphones ip in the record route. Since it's not in the
>     record route the ack from the carrier never makes it's way all the
>     back to the softphone.
>
>     This causes the softphone to keep sending 200 oks since it never
>     gets the ack.
>
>     Eventually the softphone gets tired of sending 200 oks and sends a
>     bye.
>
>     Is there any way that Kamailio can help me correct for this, or do
>     we need to have our clients use different softphones? If it has to
>     be handled via softphones is there even a softphone that can
>     account for this?
>
>     Thanks for all your assistance in advance.
>
>     All the best.
>
>     Will Ferrer
>
>     Switchsoft
>
>
>
>
>     _______________________________________________
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>
>
>
>
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