Noida-based smartphone maker Ringing Bells has launched world's cheapest smartphone priced at just Rs 251. The 3G handset, Freedom 251, features a 4-inch display, Qualcomm 1.3-GHz quad-core processor and 1 GB RAM, according to details shared by the company. However, the phone was also caught in some controversies. Also watch all other bid stories of tech and auto industry with G3.