Weird problem: ip phones rebooting at the same time

[kkj]

I too am having this problem. The strange thing about this in my case though, is that two separate groups of phones (on the same subnet), which are registered to different SIP servers, are all rebooting at the same time.

Additionally, it only affects our T38 phones. We also have T22 phones configured on the same network and same SIP servers, but they are not affected.

To give you an example, consider the following phones...
All phones HW version - 21.5.5.160.64.0.0

Phone 1
T38 - 38.70.0.186
10.0.0.21/24 - IP (Subnet A)
10.0.0.11 - SIP Server (Subnet A)

Phone 2
T38 - 38.70.0.126
10.0.0.22/24 - IP (Subnet A)
10.0.25.12 - SIP Server (Subnet B)

Phone 3
T38 - 38.70.0.171
10.0.0.23/24 - IP (Subnet A)
10.0.25.12 - SIP Server (Subnet B)

Phone 4
T38 - 38.70.0.186
10.0.0.24/24 - IP (Subnet A)
10.0.25.12 - SIP Server (Subnet B)

My suspicion is that there is a broadcast/multicast message inside the 10.0.0.0/24 network that triggers the phones to reboot. What confuses me, is the fact that it affects phones on several different servers.

Thoughts?