Verizon and AT&T plan to enable VoLTE- to-VoLTE connections between Verizon Wireless and AT&T customers in 2015. Verizon introduced its Advanced Calling 1.0 services across the United States in September.  AT&T introduced VoLTE services in its initial markets earlier this year, and continues to expand to more markets across the United States.

Engineers from both companies are working through a full set of requirements, beginning with extensive testing in lab environments and then moving to field trials.  With this approach operators aim to provide a seamless experience of making VoLTE HD Voice calls between networks and it lays the foundation for interoperability of other Rich Communications Services (RCS) such as video calls, rich messaging, and more in the future.

AT&T and Verizon Wireless have worked closely with the GSMA on this initiative. The GSMA’s Network 2020 program is designed to encourage mobile operators globally to accelerate the adoption of native IP Communication Services such as voice and video calling over LTE as well as Rich Communications Services (RCS).