We have two 2800VG boxes and we are running an Avaya VOIP between two sites over a LAN-to-LAN VPN.
We keep getting voice drop outs. "Norman Collier effect " as my colleage describes it.

I have been using ping /t x.x.x.x to fault find and I have narrowed it down to our 2800VG:
Connect the router to one PC only with a short drop lead and then on the PC run "ping /t" on the IP address of the router.
Pings are <1ms for a minute or so and then suddenly we get a slow ping... maybe 500ms, maybe 250ms - the time varies. This repeats every 30 or 40 seconds.
Obviously the router is doing some regular internal processing which is locking it up and this is causing the voice drop outs.

Is there some process we can switch off?
Anyone seen this before?