May or may not be relevant but we are using CentOS v7 and PJSIP.
I suspect it may be related to PJSIP. We have disabled that and are only using SIP for now to see if it happens again.
Seems to take a couple days of running before it happens. No calls on one server so just idling is enough. Looks like some memory leakage associated with it. Asterisk process starts out at about 60MB then goes up to about 69MB and PJSIP stops working. If we keep it running asterisk process keeps increasing. We saw it at over 100MB after a few days.
Everything still appears to be running and SIP calls from extensions still work. PJSIP calls from Trunks do not. Can’t even gracefully reboot the server. Asterisk process refuses to stop. I have to kill the process first.