Re: [SR-Users] need help for newbie in Kamailio

Hello, In SIP, session timers can be used to periodically ping the UAC (using a re-INVITE or UPDATE) to know if it's alive or not. Then action can be taken - terminating the call. Kamailio has the SST (SIP Session Timer) module which only enforces a minimum session timer value for UACs, but not a maximum one. It doesn't ping the UACs neither. This is fine because the RFC stops here. A nice improvement to Kamailio would be to augment the SST module with a feature which enforces a maximum session timer value and pings UACs. Another suggestion would be to rely on nathelper's keepalive results to take a decision after a keepalive times out, but then we'd have to terminate all dialogs in which the UAC that is not responding is present, since nathelper's keepalive are out-of-dialog. No very neat, but functional. And I don't think the dialog module can do anything about this problem. I know that what I am suggesting may not be defined in RFCs, and so are some features of SIP servers, but in my opinion should be implemented as it adds a great value to Kamailio. We cannot rely on RTP timeout since a UAC may use a silence-detection codec and be silent for some time, or may put a call on hold for a while, not sending RTP packets in both cases. This is why RTP timeout detection is not reliable. Anyway, mediaproxy timeouts ONLY AND ONLY in the case it doesn't receive RTP packets from BOTH UACs, not only one, for the reasons mentioned. I don't know about rtppoxy, maybe others can tell more about it. One solution if you really need to solve your problem would be to put a B2BUA in the SIP path, such as Asterisk or FreeSwitch. They enforce a maximum session timer which UACs can use to ping themselves every now and then, and Asterisk can even ping the UACs and terminate the call if one of them doesn't respond. The downside: lower performance and higher cost. Asterisk is very heavy and Kamailio can handle many, many more calls, so you'll have to load balance to several Asterisk servers if you have a single Kamailio machine handling thousands of simultaneous calls. Kamailio developers out there, what about boosting the SST module with new features? Or creating an SSTX module? Reda On Tue, Mar 20, 2012 at 07:35, SamyGo <govoiper(a)gmail.com> wrote: