How to use a GSM cell phone in Europe to call the USA?
 

I have a cheap unlocked GSM cell phone that I carry around while in Europe, just for emergencies, to make local calls, etc. Simply buy a new sim card for that country and pop it in the phone. Works great for that use. But, I need to make one or two calls back to the US that I have been making using a public pay phone and an AT&T prepaid phone card. Public pay phones require a coin or yet another flavor of local phone card to activate, and those that still take coins are becoming scarce in some parts of Europe. So this past trip I tried using my GSM phone, calling that countries AT&T access number for the AT&T prepaid card, but this did not work. I kept getting "number not known” when trying to dial the AT&T access number. AT&T customer service was of no help. Should this have worked? I ended up dialing direct back to the US using the GSM/sim, but burnt through the units pretty fast. Any advise on the cheapest way to call back to the USA given my scenario will be appreciated? If it makes any difference I was in the Czech Republic.

Were you using the 001 USA international code before the number? I don't have to do that on my European cell phone, but maybe you do.

Quite a few access numbers are blocked by the cellphone companies for obvious reasons. You can't always tell in advance which numbers are affected. Best you can do is to try.

My AT&T GSM phone worked fine in September as long as I dialed 001 before the US phone number. But I paid roaming charges.

When I travel in Europe I use an unlocked quadband gsm phone and an international sim, the Passport sim card sold by ekit. Phone calls to the US cost $0.49/minute, and there's a $0.35 charge for each call. Other international sims charge similar rates; see

http://www.prepaidgsm.net/en/international.html

for a few other international sim cards. The listed rates are similar to the ones I pay. I don't know the rates for local companies.