[SR-Users] Connecting UAs behind Firewall/CgNat with Kamailio without using a Stun Server

Pinter, Gerd. G.Pinter at radionrw.de
Tue May 8 08:29:42 CEST 2018

Hello Henning, hello Community

we are using high quality Codecs with bitrates up to 1500Kbit (PCM), but usually 128kbit (Mpeg1 Layer3 or AAC-LD). 128 is Not too much, but I want to be on the save side and therefore I prefer solution without Proxy.
By the way I am audio engineer at a german commercial radio broadcast network and we try to establish our own "ISDN replacement-SIP Network" for reporting from events like Soccer Games, Karneval, Rock Concerts, Political Party Summits, Lawsuits...  whatever. I want to keep frontend as simple as it gets for the reporter.
Anyway, people told me that the SIP Server of "Mayah Communications" is working without the need of stun or other Client side gadgets, but I am also told that this Mayah server works without Proxy functions. That Company won't tell me their settings of course, but if possible I'd like to have this feature for our SIP Server. At the moment I have still vast problems with connectivity from Devices that are logged on via Vodafone Mobile Network. Even Stun does not work. I guess that CGNAT of Vodafone (All of the Devices I have tested within Vodafone allocate IP Addresses in private range!) opens different Ports for different outbound connections which is the case if I use a 3rd party Stun Server. I have read a lot about this issue these days and there is solution, but I am not too deep into scripting an how to edit the kamailio.cfg. For example, I tried to start Kamailio with Stun, but if I tried to use the built in Stun, I've got error messages on the Client and also in the logfile of the SIP Server (incomplete header of Stun message) Anyone can help, please? 

Best regards Gerd

Von: Henning Westerholt <hw at kamailio.org> 
Gesendet: Montag, 7. Mai 2018 20:56
An: sr-users at lists.kamailio.org
Cc: Pinter, Gerd. <G.Pinter at radionrw.de>
Betreff: Re: [SR-Users] Connecting UAs behind Firewall/CgNat with Kamailio without using a Stun Server

Am Montag, 7. Mai 2018, 13:11:50 CEST schrieb Pinter, Gerd.:
> Hi 
> Won't RTP Proxy cause al lot of traffic? We only have 155mbit for all IT
> traffic, and our Sip Server also have to manage connections outbound our
> house, where I thought it might be better let those clients do the payload
> by peer to peer connection. If I got it right this traffic would flow thru
> our Sip server with RTP Proxy enabled.
> Thanks a lot
Hello Gerd,
you understood it correctly, indeed using rtpengine/rtpproxy would mean routing additionally your RTP traffic to your network. Depending on the number of sessions and the used codec it may work perfectly, only with some QoS tuning or not at all. You can estimate the bandwith, there are also some calculators online.
Best regards,
Henning Westerholt

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