GameStop has apparently launched their own branded mobile network named GameStop Mobile.
They are using AT&T network in the US market and users would be able to use any GSM device with their SIM cards.
The service is being offered on a contract-free model. Users get to pick from plans priced in the range of USD 5-55.
The company seems to be targeting people who buy used devices from their stores especially when they come in to trade their games and other products.