im the US.
Looks like it might have something to do with the "no ring on sleep mode"
My phone also has a problem that when its inactive for more then 1 minute it doesn't ring until you wake it up.
on another board I've seen people that have that issue also had the time being off problem.
there is no fix but a work around (or if you can exchange it apple will but since I did some "tweaks" and not activated on AT&T I can't)
check this thread
http://www.hackint0sh.org/forum/show...t=7699&page=44 there is way to replace your powersave settings, battery life is a little affected but not a lot.
just give it a shot, let your phone lay around for a while and then try it, see if it rings