we have an asterisk 184.108.40.206 running with kernel 2.6.32-31 on an UBUNTU Server.
16 SIP phones and 1 pri (30 lines) interface connectet to an berofix gateway.
The 16 agents are working with 6 queues. After some time alls sip channels are gone.
After a reboot of the asterisk daimon it work again.