Brief visit to US

[inquisitor]

They are just incompetent I guess. AT&T use exactly the same network standards as the rest of the GSM/UMTS-world including HSPA. Even if your phone wasn't compatible with their 3G network (e.g. if you had a European HTC Desire which supports UMTS only at 900 and 2100 MHz), it would still work on AT&T's 2G network.
There shouldn't be any issue except for a slightly inferior 3G coverage due to your phone not supporting UMTS at 1900 MHz.

[alect]

Originally Posted by inquisitor

They are just incompetent I guess. AT&T use exactly the same network standards as the rest of the GSM/UMTS-world including HSPA. Even if your phone wasn't compatible with their 3G network (e.g. if you had a European HTC Desire which supports UMTS only at 900 and 2100 MHz), it would still work on AT&T's 2G network.
There should absolutely be no issue except for a slightly inferior 3G coverage due to your phone not supporting UMTS at 1900 MHz.

That's what I said to my wife. Apparently the guy in the store put in a demo prepaid SIM into the phone and it didn't work so they told her not to buy since there is no refund and it doesn't seem to work.

Is it just a matter of manually rescanning networks to pickup AT&T?