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 <[email protected] <mailto:[email protected]>> 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
    <[email protected] <mailto:[email protected]>
     > <mailto:[email protected] <mailto:[email protected]>>> 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
     >> [email protected]
<mailto:[email protected]> <mailto:[email protected]
    <mailto:[email protected]>>
     >> 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
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    <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/>

    _______________________________________________
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    [email protected] <mailto:[email protected]>
    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

_______________________________________________
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[email protected]
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--
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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