設置 timer_register_expires

First of all, I am curious that how you found out the link, I created it but don't remember I advertised it anywhere. ;-)

Regarding your issue, please refer to section 2), sub-section h), SIPDefault.cnf configuration, tune up 'timer_register_expires', I changed the default from 3600 to 60, you can try other different value.

Good luck!