Re: [SR-Users] Negative ACK issue

I'm using 5.3.1+stretch from deb.kamailio.org for our new setup. Our old setup was using 4.4.4+wheezy. On Thu, Jan 9, 2020 at 9:16 AM Daniel-Constantin Mierla < miconda(a)gmail.com&gt; wrote: > 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 &lt;loi.dangthanh(a)gmail.com&gt; > 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.dangthanh(a)gmail.com >> >> >> On Thu, Jan 9, 2020 at 2:42 AM Michael Broughton < >> mbroughton(a)advanis.net&gt; 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(a)lists.kamailio.org >>> 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 >> > > _______________________________________________ > Kamailio (SER) - Users Mailing Listsr-users@lists.kamailio.orghttps://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users > > -- > Daniel-Constantin Mierla -- www.asipto.comwww.twitter.com/miconda -- www.linkedin.com/in/miconda > Kamailio World Conference - April 27-29, 2020, in Berlin -- www.kamailioworld.com > > _______________________________________________