Dollar General says it will offer T-Mobile devices with 4G and no annual contracts at its 6,400 stores. The Goodlettsville, Tenn.-based retailer says starting next month, it will offer numerous prepaid plans and the Samsung t139 phone, which features messaging, Web browsing, a camera and Bluetooth connectivity. The chain first began offering T-Mobile prepaids in 2004, and says it will offer the T-Mobile Monthly4G No Annual Contract for $50 per month. The plan offers unlimited talk, text and Web with no overage charges, and the first 100 MB of data at up to 4G speeds.