Operator-branded handsets are usually seen at the low end of the market. The smartphone makers successfully wrested most of the advantages of brand awareness – and product margins – from the operators from the iPhone launch onwards. But carriers continue to offer some devices under their own name, particularly in emerging markets, but also in developed economies. AT&T is following the trend, not just by buying handsets from a white label manufacturer, but by investing in a new device start-up itself. It has injected an undisclosed amount in Emblem Solutions. The new firm will start supplying the US operator with exclusive handsets, branded by AT&T Prepaid and the Cricket Wireless subsidiary, by the end of next year. This is more…