I am running OpenSER 1.3.1 on a Debian 4.0 system.
It seems that there's some sort of bug with OpenSER getting stuck and stops processing requests at least once a day. The logs only show the following line repeated every minute:

ERROR:registrar:update_contacts: invalid cseq for aor <1302>

At 1302 is a Cisco 7905 phone running the latest firmware. If I restart OpenSER then things get back to normal.

Does anyone know what the problem might be?