Hi, I’ve setup FreeSWITCH (using FusionPBX) to connect to the German Telekom using their SIP-Trunk product. Basically everything works fine except I have to restart the external SIP Profile every 1-2 weeks because of a 403 FORBIDDEN message returned by the Telekom server. After some investigation I think I know why this happens, but I have no idea how to solve it. The DNS SRV records from the Telekom return 3 servers with different priorities. - You can check that with: nslookup -querytype=SRV _sip._tcp.reg.sip-trunk.telekom.de FreeSWITCH takes the one with the highest prio and registers. - e.g. serverA - Also every 240 seconds a re-registration happens Then everything works as expected - All INVITES go to serverA as well (because reg.sip-trunk.telekom.de is also the outbound proxy) Once in a while the Telekom changes the prio of the servers - So the next INVITE goes to serverB - And this is where I get the 403 because they expect the INVITE to be sent to the server FreeSWITCH registered before (in this example serverA) So I see two problems here I’d like to solve: When re-registering every 240 seconds it looks like FreeSWITCH doesn’t do another DNS lookup and doesn’t re-register to the server with highest prio - How can I force FreeSWITCH to do this DNS lookup before every registration and choose the new “best” server? - How can I force FreeSWITCH to send the INVITES to the server it registered before (and not to the one with the currently highest prio)? When doing some research I found the 3CX has some new option implemented especially for this problem: “Force invites to be send to IP of registrar” Please see: https://www.3cx.de/blog/deutsche-telekom-sip-trunk-wichtig/ Is something like this also possible with FreeSWITCH? Thanks, Klaus
Hi Klaus, I had some DNS issue with DTAG years ago, admittedly on a subscriber SIP line, until somebody suggested to use the DTAG nameserver instead of the third party nameserver I was using back then. Problem solved. Maybe the fix for you is the same. Regards, Seb
Hi Seb, thanks, but already did that. I have a local Unbound DNS server running which forwards (without caching) the DTAG domains directly to the DTAG DNS server and all others to the router. But didn't help... Best Regards, Klaus -----Ursprüngliche Nachricht----- Von: Sebastian Kemper <sebastian_ml@gmx.net> Gesendet: Dienstag, 27. November 2018 19:09 An: FreeSWITCH Users Help <freeswitch-users@lists.freeswitch.org>; ITutu - Mailings <mailings@itutu.de> Betreff: Re: [Freeswitch-users] Problem with German Telekom SIP Trunk Hi Klaus, I had some DNS issue with DTAG years ago, admittedly on a subscriber SIP line, until somebody suggested to use the DTAG nameserver instead of the third party nameserver I was using back then. Problem solved. Maybe the fix for you is the same. Regards, Seb
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Sebastian Kemper