AT&T, T-Mobile, and Verizon have agreed to work together under a new joint venture that aims to end wireless dead zones in the US. The partnership was announced today as an "agreement in principle," but if finalized would see the three carrier companies pooling their ground-based spectrum resources together to increase coverage in rural areas. The goal is to create the "best and most diverse ecosystem for wireless and satellite products and services," though details on how this will actually be