hey, thanks for replying.
I haven't tried the radio trick as I'm not at the location that's having the issue. The connection died completely this morning, around the time of the massive spike.
On the 2wire log, I see this:
Uncanceled Echo: 12.3 dB Suspicious - check phone filters and alarm
Training history:
ERR_INCONSISTENT_SIGNAL
It's a brand new telphone line, the router is plugged directly into the master socket. Filter and telephone cable has been changed.
The problem seems particulary bad between 8-9, lunchtime and a few spikes through the day.