I have a problem with my my IP phones, atleast once in every 15-20mins. all my IP phones gets rebooted & come back, some time If I initiate call or some one calls me it immediately gets rebooted. Any idea what could be causing this issue. This is happening in one of our branch office which is connected to our Main office CCM 4.1 over the VPN. VPN seems to be OK, only issue is the IP phones in the branch offices gets rebooted & not in the head office.
My IP phones in branch offices are 7940 & 7960