[potatolicious]

Well, the problem is that densely populated countries and cities like most of western Europe also don't seem to have any issues running a stable, fast network.

So... density really isn't much of a variable here.

Oh, also, I have it on reliable information that iPhone network stability and speed in Toronto, Canada is very, very good. This is a city that's denser than most major American cities, especially notable cities where network stability sucks.

[docmach]

That seems like a much better comparison. However, what it leaves out is the network usage. Maybe there aren't as many people using one carrier's towers in those other places or maybe the usage isn't as heavy. So while we know that AT&T's network can't handle the load we don't know if it's because of an inferior network or because of higher usage. I would be interested in seeing those kind of statistics compared for well performing and poorly performing networks, but I don't know if that information will ever be available.