Been using sipgate for a month or two. Been pretty happy with it so far. Free to sign up, geographic number and the acount managment website is pretty good.

Only downside I can see if that if you say credit your account with £10 and then leave, you can't get the £10 refunded. But thats no issue unless the whole service goes to pot and you want to leave.

The forwarding of viocemails as attachments to emails is a good idea, and useful to me when out and about as i can pick up voicemails via email.

I don't really have other VOIP providers to compare to (as I've not used them). But sipgate seemed the sensible one for me.