Best Buy and Carphone Warehouse have announced their trial of Best Buy Mobile stores a success. The companies will expand on the concept and launch 150 to 200 stores over the next 18 months. They will open a mix of stand-alone and store-within-a-store locations throughout New York, Texas and the Boston area. The stores offer a mix of services from pre-paid and post-paid carriers, giving customers a wide choice of phones in a single location.