Take a look at http://bugs.digium.com/view.php?id=7351
Might be related. I've seen this too. There's a (very simple) patch attached which you can try.
-----Original Message----- From: users-bounces@openser.org [mailto:users-bounces@openser.org] On Behalf Of David Coulthart Sent: Wednesday, May 30, 2007 10:49 AM To: users@openser.org Subject: [Users] Malformed CANCEL request from Asterisk possibly impactingOpenSER?
We are currently experiencing problems with our production OpenSER (1.1.0) environment where the load on the server is steadily increasing and the OpenSER response time increases drastically (e.g., 30+ seconds for an internal call to ring).