AT&T Aircard 781S Hotspot Battery 3.7V 2400mAh Li-ion ATP781RX The Cameron Sino ATP781RX battery is a direct replacement for specific AT&T Home and Office Equipment Batteries. See below which model, or part number, this battery is a replacement for. What is a Replacement Battery? Why should I choose a Cameron Sino Replacement / After Market Battery? Because Cameron Sino Batteries have better performance (higher capacity) and reliability (longevity and safety). This superior performance improves batteries’ running time, which is often better than the original brand replacement. This superior quality results in longer battery life and better protection of the powered device. All products are passed through a QA department which help Cameron Sino to achieve the lowest return rate in the industry.