This has occurred with a number of recent revisions. If anyone can reproduce it or suggest debugging steps, I'll gladly supply more information. Jira isn't convenient for me due to X issues at the moment, unless there's a way to interact with it other than via a Javascript-capable Web browser. Distribution: Debian Sid, now kernel 2.6.29 (same experience with 2.6.26). FreeSwitch revision 12701. Steps to reproduce Make a call with portAudio to a SIP endpoint (I haven't tried it with other endpoints): pa call <destination> Next, make another call: pa call <other_destination> Result: the party to the first call hears no music on hold, or possibly broken/intermittent music on hold, and the second call fails to go through. Where it hangs seems to vary, and sometimes it does in fact work. Often it hangs before it reaches the calling state, suggesting that there's some kind of locking issue involved. I'll perform further testing. Meanwhile, if anyone else can reproduce it, this may help. Note that the second call often doesn't return an error; it just hangs somewhere in the set-up process, e.g., init.