Originally Posted by aau007
As far as I was told, Cingular has setup "free roaming" with ATT. You Cingular phone may have a preference on Cingular tower but you will also pick up ATT towers and no roaming charge will be incurred and vice versa. That being said, without some "integration", I am not sure your call will hop back and forth between Cingular and ATT tower during the same call. No one I talked to are technical enough to answer that question.
Cingular's "free roaming" with ATT, and other carriers, is no different than what Cingular customers had before the merger. There's been no improvement in coverage for Cingular customers, and won't be for years, that I can see. The problem with Cingular's "free" roaming is that Cingular requires your unit to be almost totally out of coverage with its towers, before it allows you to roam to another tower, no matter how powerful a signal an adjacent alien tower may be emitting. So I'd rather be "homed" into the ATT towers, and roam onto Cingular when its towers are stronger, which is seldom the case in my area.
I've tried to switch carriers manually on my 7290, as suggested in other threads, but my device does not allow this function. The carrier is stuck on Cingular, and there's no option to opt out. Same when I do roam onto an alien carrier's towers, and I'm trying to get back to Cingular manually (in my case because I live on the Texas side of the Mexican border and the alien towers are Telcel and something called APU.