T-Mobile, a part of EE, previously offered 3G internet with the option of unlimited data. They also offered Smart Packs on Pay As You Go.
As of February 2015, the T-Mobile brand is no longer available to new or upgrading customers. Existing customers already on T-Mobile can stay on their existing plan “for as long as they like”. New or upgrading customers will need to choose a tariff from EE.
The following articles provide information for existing customers who are already on T-Mobile: