Cingular is the only one who works in San Antonio when more than 3 people are in the same place. Forget concerts, Spurs games, HS football games, festivals and parades if you use anybody else. Have NEVER figured that one out.
BTW - I am on ATT and always am dropped in about 8 parts of town. I am the apologetic dude, "OK, I am about to go into an area that drops me, If it hangs up, I'll call you right back."