Originally Posted by onofre
If you have AT&T GSM service there now is no charge for roaming on any other GSM carriers. So, if Cingular has a stronger signal you may roam onto them but can still make calls exactly as if you were using AT&T.
I've used AT&T in Manhattan and it seems to be pretty good.
Actually, there some ATT GSM plans that do not include all across the country, anywhere you get a signal roaming. So, be sure not to get a local plan or restricted plan. They will still charge you roaming. Indeed, most plans have this.
As for just like ATT, remember though in your home area, say area code 415 or 212, you do not have to dial an area code to connect, just seven digits, so you might have only seven digits programmed in your phone book, but while roaming on cingular, they authorize access, but dont' know your home zone, so you will have to dial area codes to connect. This is not very clear and people think they cannot connect when they get the fast busy, or other no connection signal. It seems strange sometimes to dial your home area code, to call HOME while in your HOME area, but that is what is necessary.