forgive me if this is hella-obvious but it’s necessary to check :
You don’t happen to have a statement in modules.conf that’s stopping the sip module from being loaded do you ? If you see something like “noload => chan_sip.so” in your modules.conf, and you’re using autoload, get rid of it. If not, it seems as if your sip module may not be in the modules dir, or you have a 1.0.x module in a 1.2.x directory. I’m not versed enough to know if your sip/extensions syntax is completely correct, but syntax errors should not be causing the module to not load, which is the #1 reason for udp/5060 to not be listening.