T-Mobile is a European carrier, a subsidiary of Deutsche Telekom.
Telefonica is a European telecommunications carrier usually known as the brand O2.
Metro PCS provides wireless services on a no long-term contract, flat rate, unlimited usage basis in selected major metropolitan areas in the United States.
Bell Wireless is a large Canadian CDMA provider featuring phones from LG, Motorola, Blackberry, Samsung and more.
Helio is a US wireless provider of 4 co-branded Samsung phones called Ocean, Mysto, Fin, and Heat featuring unique multimedia support. Don't call it a phone.
Cricket is a North American wireless provider featuring phones from Kyocera, Samsung, Nokia, Motorola, and others.