On September 6, T-Mobile will launch its new T-Mobile ONE Plan, which will offer unlimited talk, texts, and 4G data. Your first line will cost $70 per month; the second costs $50 a month, and additional lines add $20 a month up to eight lines. It also offers unlimited LTE data on tablets for an additional $20 per month. The initial roll-out will be for post-paid customers only, with prepaid plans becoming available later. For more information, click here.