Yep, I worked on AT&T's ATG-based implementation for their mobile dumbphones. Once you get on ATG it's mighty hard to get off, even if it's costing you millions of dollars in licensing/support fees.
Back then, their product really was one of the best. You had Dynamo and Sapphire (now owned by HP I think), then a big gap, then WebLogic that was only being used by existing BEA shops, then another big gap, then Sun/Netscape's awful iPlanet thing.
