On Mar 2, 2021, at 11:19 AM, Sergiu Pojoga &lt;pojogas(a)gmail.com&gt; wrote: Are you supporting a single Contact per AoR? Otherwise, I don't see how you can keep track of "changes in location and detect if an agent is online". If so, just set the 0x04 registrar flag and you'll always have the latest registered Contact address in Location. https://kamailio.org/docs/modules/devel/modules/registrar.html#registrar.f.… <https://kamailio.org/docs/modules/devel/modules/registrar.html#registrar.f.save> Regards, --Sergiu On Tue, Mar 2, 2021 at 8:26 AM Michal Popovic &lt;michal.popovic(a)cloudtalk.io <mailto:michal.popovic@cloudtalk.io>> wrote: Hello everybody, let's have a situation where UAC is behind the NAT and router suddenly change the external port. Kamailio in this case creates two location entries one with old port and one with the new one. Now UAC unregister from the new one and old location remains active until it expires and our support system that is listening to locations changes keep the agent online for other services. Is there any way besides the regular OPTIONS ping from UAS to UAC how to solve this issue? Thanks. Michal _______________________________________________ Kamailio (SER) - Users Mailing List sr-users(a)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> _______________________________________________ Kamailio (SER) - Users Mailing List sr-users(a)lists.kamailio.org https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users