T-Mobile is currently offering AT&T customers who make the switch with a 128 GB iPhone for the price of a 16 GB model, giving them a U.S. $200 discount should they transfer to T-Mobile's service. The move follows the company's plans to tempt Sprint customers with an extra $200 on top of their existing credit for every handset line they bring over to T-Mobile.

According to reports, the price cut is a bill credit, and the offer will only last until Dec. 13 of this year. Furthermore, T-Mobile will also be responsible for paying the early termination fees that will consequently come with the switch.

T-Mobile is also offering discounts as much as half of the price tag of the accessories that it is carrying. These items include headphones, wearables, wireless speakers and more.

"I can already hear AT&T customers asking 'What's the catch?' And I don't blame them -- because with AT&T there's always a catch," John Legere, Chief Executive and President of T-Mobile, said. The company promises that there would not be only one, which is making it too difficult a deal to pass up while it still lasts.

T-Mobile has first lured the Sprint customers by offering a month-long promo that gives an extra $200 on top of a customer's existing credit for every handset that they bring over to T-Mobile's service, no matter if it is a prepaid plan or a postpaid subscription. The move is apparently a part of the former's feud with the latter, and it has yielded continuous benefits for the customers.

The T-Mobile will also offer customers who are currently subscribed to Big Red's services soon, as T-Mobile says that the offer is on its way to Verizon customers as well.