the people i know that uses tdma att in coco county hates tdma. i hear the gsm is pretty cool. i use cingular. i think cing and att shares network in the bay. from what i was told. att patched holes that cing has in the bay with 850band. as long as you have 850 and 1900 band on the phone you get then coverage should be cool. i found very small dead spots on i80 that i may drop calls( se t616) but thats it. i travel from vallejo to sf. everyday and stop in richmond and i enjoy my phone. even had cool signal at san pablo resevior/kennedy grove park. also have full signal inside caldacot tunnel. hope this helps.