Is it a recent version of kamailio, or an older one? Cheers, Daniel
On 09.01.20 16:55, Michael Broughton wrote: > Thank you, this was a helpful sanity check. > > We have been capturing SIP traces to try and debug this. I normally > just look at the traffic on our Kam box because it is convenient to do > so, but I have also taken traces on our firewall to check the ALG > behaviour. The provider techs are also tracing these calls on their > network as well. The ALG is new equipment in our setup, but as far as > I can tell it is behaving correctly. > > The one rather annoying discovery that I made is that when I call > directly out from the source (Freeswitch in this case) and bypass > Kamailio, the negative ACK's seem to work. I do not see any > retransmissions of their final response. And of course the only > significant difference in the SIP traces is the Via headers. > > Anyway, thanks again for your input. > > > On Thu, Jan 9, 2020 at 4:04 AM Lợi Đặng <loi.dangth...@gmail.com > <mailto:loi.dangth...@gmail.com>> wrote: > > Hi, > You're not going to have the Via header from your `source` sent to > your `telco provider` in the negative ACK when the call is not > answered, because the ACK in the right hand side of the call is > created by the kamailio itself, not a forwarding one by the `source`. > Yes, you've guessed it, ACK for an answered call is a forwarding > one which contains all the Via headers. It's the SIP spec, not > kamailio, you may want to dive into rfc3261 for more details. > > In this case, your telco's expectation is not correct, my best > guess is something went wrong with either your SIP ALG or Telco > Provider. SIP capturing may help. > > rgds, > Loi Dang Thanh > Phone : +84. 774.735.448 > Email : loi.dangth...@gmail.com <mailto:loi.dangth...@gmail.com> > > > On Thu, Jan 9, 2020 at 2:42 AM Michael Broughton > <mbrough...@advanis.net <mailto:mbrough...@advanis.net>> wrote: > > Hello, > > Long time Kam/Ser user, first time poster. > > I'm running into a problem with one of our telco providers > when we make a call that ends up being not in service or some > other error. In this case our ACK's are not working and the > phone line stays open for a period of time until something > times out on their end. > > They claim the issue is that our negative ACK message is > dropping one of the Via headers. This is the only case I can > find in our setup where Kamailio does this. But it does drop > the first Via, which is the first hop in our internal network. > > I don't understand why this is a problem for them, and I'm > still trying to get a reasonable explanation out of them. > Technically, I don't see why it would be a problem. This > behaviour is not an issue with our other telco providers. > Strangely enough, it is also not an issue for this provider > when we make the calls over their MPLS network (we are > switching to the internet). > > My question is, can this behaviour be changed in Kamailio > somehow? Is there a way for it to keep all the Via headers for > negative ACK's? > > Or, do I just need to poke them harder to fix their issues? > > My setup: > > Source -> Kamailio -> Firewall (NAT, SIP ALG) -> Telco Provider > > I hope I have provided enough information. > > Thanks! > Michael > > > _______________________________________________ > 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 > > _______________________________________________ > 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 > > > _______________________________________________ > Kamailio (SER) - Users Mailing List > sr-users@lists.kamailio.org > https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users -- Daniel-Constantin Mierla -- www.asipto.com www.twitter.com/miconda -- www.linkedin.com/in/miconda Kamailio World Conference - April 27-29, 2020, in Berlin -- www.kamailioworld.com
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