A push by a coalition of telecom operators, device makers, and industry groups to bring $40 smartphones to market — a price point seen as key to getting tens of millions more people online — is gathering momentum, but questions remain over whether manufacturers can produce such ultra-low-cost devices at scale. This week at Mobile World Congress in Barcelona, the advocacy and lobbying group GSMA said it is working with major African mobile operators — including Airtel, Axian Telecom, Ethio Telecom, MTN Group, Orange, and Vodafone — and smartphone makers to pilot ultra-low-cost 4G devices in six African markets: the Democratic Republic of the Congo, Ethiopia, Nigeria, Rwanda, Tanzania, and Uganda, in a bid to make smartphones more affordable and bring an additional 20 million people online.…