I seem to be running into this bug as well. I also have 1:1.6.2.0~dfsg~beta3-1 and my Asterisk has become unstable since I installed it because of these chan_sip.so crashes. The crash happens very often. I haven't been able to obtain a coredump but I see in dmesg's output the following:
asterisk[26084]: segfault at c ip b690b093 sp b5252b00 error 4 in chan_sip.so[b68d8000+7b000] Eloy Paris.- -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org