AT&T is ready to launch Voice over LTE in select markets in the US, Telecompaper.com reports, citing Engadget. The roll-out is expected to start May 23, initially in Chicago and Minneapolis. This would be the first major deployment of VoLTE on a tier 1 network.

The technology uses the 4G network to route voice calls. To date, most operators have relied on circuit-switched fallback to route customers to the 3G network for voice, reserving the 4G network for data. Phones will require an update in order to support the voice service. AT&T said it was in the process of completing its initial VoLTE market trials, and initial markets will be VoLTE ready this year.