I use Asterisk 188.8.131.52. Some time suddenly call drops. It append without any noise or click. Just silence. I don’t find any thing on logs talking about call drops. I compiled Asterisk on linux Slackware, my kernel is 3.3.1, maybe I will compile new version soon.
You will have to give us more info about your system.
What kind of phones are you using (analog phones, IP Phones)?
How are you connecting to the public telephony network (VoIP provider, ISDN, analog)?
Are you using any interface cards or gateways?