Trouble with SIP registering
 

I've recently set up a SIP account with voip.co.uk and am having trouble getting it to work with my n900.

From my computer I can make and receive calls fine.

From my n900 I can make calls no problem, but can't receive, even though the availability is online. I've checked with voip.co.uk and they've said they're not even receiving any traffic from the phone.

Any idea how to log what the phone is doing in terms of registering?

Thanks,
Chris