[puddintane]

T-Mobile as well here and I have never once received a robocall.

I wonder if they are actively trying to do something to prevent this already and now AT&T wants to join?

[maxerickson]

I would guess it comes down to the old rules about telemarketers not calling cell phones. If you are in a 'pure' cell phone exchange (the 3 digits after the area code), the number is probably excluded from some dialing lists by inertia.