Dear all, We're experiencing some (what appear to be) deadlocks using asterisk-1.4.35 (the problem also occurred on 1.4.24). Some of the symptoms are that new SIP calls cannot be established and when running "sip show channels" from the CLI, the CLI stops responding to any further commands. The symptoms are in fact very similar to https://issues.asterisk.org/view.php?id=15349. A possibly significant difference is that once asterisk hangs and I try to stop or kill it, asterisk will remain as a defunct process and I have to reboot the machine to get things working again. Two servers are involved, both running asterisk 1.4.35, both have a TC400B card used for G729 transcoding and both are equipped with a Sangoma A104dm card connected to 4x ISDN-30. Server A is the main server (holds all phone registrations, does all the monitoring/recording, all outgoing calls originate here and all incoming calls terminate here). Server B acts as a SIP trunk in a neighboring country (connected by a stable, dedicated and private link). Every once in a while (about 2-4 times a week), either one of the servers stops setting up new SIP channels, something we haven't experienced before on other sites (only significant difference is that the other sites use an older version of asterisk and lack a transcoder card). I've managed to get the output of "core show locks" (available here: http://pastebin.com/S870RSi3), unfortunately, I haven't been able to collect a backtrace yet. Now down to my question: What I'd like to know is how to properly debug this issue further. On a side-note, there are a couple of problems with debugging this issue: a) We've been unable to reproduce it locally. Actively trying to reproduce it on the production machine is a no-go due to contracts with the customers. And b) once the system does hang, we have very little time to poke around (again, because of contracts), the system has to be up and running as soon as possible. Kind regards, Ingmar Steen Teleknowledge