T-Mobile announced on Thursday that it has officially activated its voice-over-LTE (VoLTE) network in Seattle. The news follows a similar announcement from AT&T, which is activating VoLTE service in select markets tomorrow, May 23. T-Mobile said that the move to VoLTE is a huge milestone in the progression of its network, and that VoLTE will still include the “HD Voice” calls that it already offers nationwide.

T-Mobile’s chief technology officer Neville Ray explained some of the benefits in a blog post Thursday. ” Customer benefits include faster call setup times (almost twice as fast as a non-VoLTE call setup) and the ability to enjoy lightening fast LTE data speeds while on a call,” he explained. AT&T and T-Mobile already allow for data transfers while on a call, but this moves the voice calls from the older HSPA+ network to a newer LTE network. Instead of being routed through a circuit switcher, calls are carried over IP, Neville explained. When LTE isn’t available, calls will then automatically route back over HSPA+ networks.

T-Mobile already has a few devices that support VoLTE and, after a quick software update, you can test the service for yourself in Seattle. Supported handsets include the LG G Flex, the Samsung Galaxy Note 3 and the Samsung Galaxy Light. If you’re in T-Mobile’s VoLTE market, give it a test and let us know if you can tell the difference.

Source T-Mobile