they're not going to be running on one signal all AT&T customers will still be running on AT&T signal and T-Mobile will still be on T-Mobile signal. if they want everyone to be on one signal AT&T is going to have to provide all T-Mobile customer with new phones or spend billions more to inner-grade both signal to work as one which i see neither happening after this 39 billion they just drop for T-Mobile. is going to be duel layer system for the 4G customers they are going to run both HSPA and LTE. they was behind of Verizon LTE system so rather then use the money to develop and improve their own LTE (4G) they just brought T-Mobile HSPA towers. our plans will change. if you're contract is up with T-Mobile but you are still with them when the switch happen AT&T is going to force you to sign a new contract and get you to pay for an AT&T phone to get on their network. if you are still under T-mobile contract at the time of the switch you will be grandfather in meaning you will still have your unlimited plan but only till your contract is up then you will have to sign a new one with AT&T and pay for a new phone to work on the network. all the romors that AT&T is going to bring back their unlimited plan are faults. they have already started to limit the data transfers on their own u-verse tv and their DSL internet and if you go over they are going to charge you for it. their network is old and can't handle all of this data so you're going to have to pay if you wanna play for the data you use.