Thanks Alex!


On Thu, 10 Dec 2020 at 14:09, Alex Balashov <abalashov@evaristesys.com> wrote:
if(has_body("application/sdp") && search("a=sendonly")) [1]

It's what comes to mind off the top of my head, anyway.

-- Alex

[1] https://www.kamailio.org/docs/modules/stable/modules/textops.html

On 12/9/20 7:43 PM, David Cunningham wrote:
> Hi Alex,
>
> Thank you for that. Do you offhand know of an easy way to test if the
> sendonly attribute is set? Presumably we can use
> sdp_remove_line_by_prefix() to remove it.,
>
>
> On Wed, 9 Dec 2020 at 20:52, Alex Balashov <abalashov@evaristesys.com
> <mailto:abalashov@evaristesys.com>> wrote:
>
>     The salient quality of a reinvite is that has_totag() == true; it is
>     handled in the loose_route() section of your config. You want to do the
>     SDP manipulation in the part below that, where initial INVITEs are
>     handled.
>
>     On 12/9/20 2:47 AM, David Cunningham wrote:
>      > Hi Daniel,
>      >
>      > Removing the sendonly from the INVITE SDP sounds like the most
>     workable
>      > solution in our case. We'd only want to do it for a new INVITE
>     though,
>      > not a re-INVITE in a situation where a call is put on hold. Would
>     you be
>      > able to give an example of such a configuration?
>      >
>      > Thanks very much for your help!
>      >
>      >
>      > On Tue, 8 Dec 2020 at 21:56, Daniel-Constantin Mierla
>     <miconda@gmail.com <mailto:miconda@gmail.com>
>      > <mailto:miconda@gmail.com <mailto:miconda@gmail.com>>> wrote:
>      >
>      >     Hello,
>      >
>      >     if the endpoint is not behind a port forwarding nat/firewall
>     (when
>      >     one can instruct the rtp relay to use signaling address), then
>      >     probably you can try to remove the sendonly from the INVITE SDP.
>      >     That will enable rtp from endpoint to doorbell, which may rise
>      >     additional concerns (e.g., privacy) if its is explicitly not
>     wanted
>      >     to happen. But as Alex said in another response, the only way
>     to get
>      >     it work is to make the endpoint behind nat to send a RTP packet.
>      >     Usually the doorbells I encountered so far were accepting
>     incoming
>      >     traffic as well, to discuss/interact with the person ringing
>     on it.
>      >
>      >     Cheers,
>      >     Daniel
>      >
>      >     On 08.12.20 05:01, David Cunningham wrote:
>      >>     Hello,
>      >>
>      >>     We have a problem with a SIP doorbell device which sends
>     media one
>      >>     way only, and NAT at the receiving device.
>      >>
>      >>     When the doorbell button is pressed it makes a call to a
>      >>     configured destination. Since the doorbell only sends and
>     doesn't
>      >>     receive it sends the INVITE with sendonly in the SDP, and the
>      >>     destination then replies with a 200 OK with recvonly in the SDP.
>      >>     The problem is that the destination is behind NAT, and its reply
>      >>     contains a private network IP in the SDP.
>      >>
>      >>     Normally Asterisk when nat=yes works around that by
>     adjusting the
>      >>     destination for RTP to be the address it actually receives audio
>      >>     from, however because this device is recvonly Asterisk never
>      >>     receives audio from it. This means Asterisk keeps trying to send
>      >>     the doorbell's RTP to the private network IP which of course
>      >>     fails, and the destination never gets the RTP from the doorbell.
>      >>
>      >>     We haven't found a solution in Asterisk to this, so are now
>      >>     looking to Kamailio which acts as a load-balancing proxy in
>     front
>      >>     of Asterisk for one. For example, maybe we could use
>      >>     fix_nated_sdp, but only on 200 OK's with recvonly.
>      >>
>      >>     Has anyone else encountered this, and are there any recommended
>      >>     solutions?
>      >>
>      >>     Thank you in advance!
>      >>
>      >>     --
>      >>     David Cunningham, Voisonics Limited
>      >> http://voisonics.com/ <http://voisonics.com/>
>     <http://voisonics.com/ <http://voisonics.com/>>
>      >>     USA: +1 213 221 1092
>      >>     New Zealand: +64 (0)28 2558 3782
>      >>
>      >>     _______________________________________________
>      >>     Kamailio (SER) - Users Mailing List
>      >> sr-users@lists.kamailio.org
>     <mailto:sr-users@lists.kamailio.org>
>     <mailto:sr-users@lists.kamailio.org
>     <mailto:sr-users@lists.kamailio.org>>
>      >> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>     <https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users>
>     <https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>     <https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users>>
>      >
>      >     --
>      >     Daniel-Constantin Mierla --www.asipto.com
>     <http://www.asipto.com>  <http://www.asipto.com <http://www.asipto.com>>
>      > www.twitter.com/miconda <http://www.twitter.com/miconda>
>     <http://www.twitter.com/miconda <http://www.twitter.com/miconda>>
>     --www.linkedin.com/in/miconda <http://www.linkedin.com/in/miconda>
>     <http://www.linkedin.com/in/miconda
>     <http://www.linkedin.com/in/miconda>>
>      >     Funding:https://www.paypal.me/dcmierla
>     <https://www.paypal.me/dcmierla>  <https://www.paypal.me/dcmierla
>     <https://www.paypal.me/dcmierla>>
>      >
>      >
>      >
>      > --
>      > David Cunningham, Voisonics Limited
>      > http://voisonics.com/ <http://voisonics.com/>
>     <http://voisonics.com/ <http://voisonics.com/>>
>      > USA: +1 213 221 1092
>      > New Zealand: +64 (0)28 2558 3782
>      >
>      > _______________________________________________
>      > Kamailio (SER) - Users Mailing List
>      > sr-users@lists.kamailio.org <mailto:sr-users@lists.kamailio.org>
>      > https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>     <https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users>
>      >
>
>     --
>     Alex Balashov | Principal | Evariste Systems LLC
>
>     Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
>     Web: http://www.evaristesys.com/ <http://www.evaristesys.com/>,
>     http://www.csrpswitch.com/ <http://www.csrpswitch.com/>
>
>     _______________________________________________
>     Kamailio (SER) - Users Mailing List
>     sr-users@lists.kamailio.org <mailto:sr-users@lists.kamailio.org>
>     https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>     <https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users>
>
>
>
> --
> David Cunningham, Voisonics Limited
> http://voisonics.com/ <http://voisonics.com/>
> USA: +1 213 221 1092
> New Zealand: +64 (0)28 2558 3782
>
> _______________________________________________
> Kamailio (SER) - Users Mailing List
> sr-users@lists.kamailio.org
> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>

--
Alex Balashov | Principal | Evariste Systems LLC

Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/

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--
David Cunningham, Voisonics Limited
http://voisonics.com/
USA: +1 213 221 1092
New Zealand: +64 (0)28 2558 3782