I'm curious to know how roaming works with cell phones. My sister and I just completed a road trip from St. Louis, to Washington DC. I have Cingular, she has T-Mobile. While we were in the middle of nowhere, there were a few cases where I had a signal and she didn't, and vice versa. For example, in Charleston, WV, she was roaming onto West Virginia Wireless's network, while I was still on Cingular. But then, further east of Charleston, I lost signal and she was still on WVW's network. Now, when my phone detects that there's no Cingular towers, shouldn't it also have roamed onto WVW? Likewise, there was another time when I was full signal on Cingular, and she had no signal. Shouldn't her phone have roamed onto Cingular's network? Or when I had nothing and she had full signal on T-Mobile's network, shouldn't my phone have roamed onto T's network? Throughout the trip, I never went onto any other network. It was either Cingular, or nothing. I guess I'm not understanding when a phone goes onto another company's network, and when it doesn't. Thanks.