To this point, Long Term Evolution (LTE) has been all about data. Mobile voice is handled by companion protocols.
That's changing. Increasingly, vendors and service providers are seeking to send voice as well as data on a 4G LTE stream. At the Mobile World Congress in Barcelona, Verizon Wireless announced that it successfully ran voice over two LG Revolution LTE handsets over a network in Basking Ridge, N.J. The tests, Connected Planet reports, lasted more than 10 minutes and included simultaneous surfing and app downloads. The story provides a good rundown of what the issue is, including this paragraph:
Shoehorning voice into what was designed entirely as a data network has been one of the more controversial issues surrounding LTE. VoIP has already begun to proliferate over mobile data networks via over-the-top services like Skype, but no operator has developed a carrier-grade VoIP service it could use to compliment, and eventually replace, their 2G circuit-switched voice services.
AT&T seems to be running a bit behind Verizon. Forbes' Elizabeth Voyke writes that Verizon is aiming to offer the service-Voice over LTE or VoLTE-in 2012 and AT&T in 2013. She cites AT&T CTO John Donovan's opinion that apps will emerge in the interim that will bolt voice on LTE. This, in essence, will hold the fort until VoLTE-a more fundamental marriage of voice and data-arrives. The post positions VoLTE as one element of a much broader transition for the carrier:
VoLTE is part of AT&T's seven-year roadmap to evolve voice services on its network. Much of the work involves deploying more efficient and versatile technologies and transitioning customers to them. The goal is to consolidate disparate voice platforms to a common or converged core that will provide more flexibility on different types of user interfaces.
VoLTE is the new name of One Voice, an initiative that PC World reports has grown from a dozen vendor and service provider supporters to more than 40. The organization was formed in November, and the article suggests that the rapid growth in support is key as telecommunications companies seek to avoid technical fragmentation in approaches to LTE voice.
Vendors are getting into the act as well. At the LTE TDD/FDD International Summit organized by China Mobile at the MWC in Barcelona, Ericsson and two related companies-Sony Ericsson and ST-Ericsson-demonstrated a Time Division-Long Term Evolution (TD-LTE) network that supports voice as well as video streaming, Web browsing and other applications.
It pays to remember, however, that LTE voice still is a future-oriented technology. Airvana and Freescale today announced an LTE femtocell that supports LTE but relies on 3G voice.