Here's our story. Server in the home country, colo server in the USA. In between a rather restrictive firewall run by our ISP that I can't do anything about. Our linux firewall keeps UDP state information for 180 seconds. Unfortunately the other firewall in the middle seems to be about 30 seconds, and it won't pass port 4569 without it. So, I need to reduce the refresh time to match. I can't find any information on how to do it via iax2.conf, and in fact have come to the conclusion that it's not possible right now. Although I'd like to change it on a per peer basis (so as not to annoy iaxtel which is only used for outgoing anyway), i've tried to change it in the source, specifically the constant IAX_DEFAULT_REG_EXPIRE in iax2.h. This doesn't work either. I actually got it to use the new time (28 seconds) for the first registration by just throwing that number in a bunch of places, but it goes back to 60 after that, and that was really messy anyway.