by Vicki Livingston, Head of Communications, 4G Americas

From the first batters up to the plate in South Korea in 2012, with a flurry from Metro PCS in the U.S., Voice over LTE (VoLTE) seemed to be in a field of dreams and not making much noise or progress. However, bring it on baby... as VoLTE may be getting ready for prime time in 2014. Analyst firm Infonetics expects 30 commercial networks and 51 million subscribers with VoLTE by the end of this year and that number will grow to the major leagues on 2015.

So, what is it? And why is it good?

Voice over LTE provides operators with a complete solution to evolve their voice business towards an all-IP communications network. This happens when the circuit-switched (CS) core network moves to an IP Multimedia Subsystem (IMS) core network, which supports communication services like High Definition (HD) voice, video calling, Wi-Fi calling and Rich Communications Services (RCS). This is an end-to-end network infrastructure solution including IMS, Evolved Packet Core, LTE-Radio Access Network (RAN) and system integration services.

The good news is that research (conducted by Michael Thelander's Signals Research) has shown VoLTE to be hitting home runs. In tests in Minneapolis, Signals found that "VoLTE is pretty much everything that we hoped it would be": 1) call quality greatly exceeded that of 3G CS voice and was measurably higher than Skype voice over either WiFi or LTE; 2) call set up time was greatly improved from 3G CS voice which took nearly twice the time as a VoLTE call; and 3) VoLTE required substantially fewer network resources than Skype and presumably other Over-the-Top (OTT) voice applications which resulted in a longer estimated battery life.  Signals further noted that additional positive network and user experience implications are likely as VoLTE matures and LTE coverage improves due to fewer handovers to the 3G CS network. According to the report, operators should strongly consider the long-term network cost savings associated with VoLTE given that it is far more efficient when it comes to supporting a voice call compared with OTT voice applications.

Tied to the many benefits for consumers and operators is the future-proof path for VoLTE. VoLTE dates back to early 3GPP Release 7 standards with ongoing work. Offering a VoLTE service may seem easy, but it's not-that explains the delay between early 2012 launches and 2014-2015 when VoLTE will be more widely deployed.

For those ready to dig in their heels for the fast pitch, 4G Americas published a free white paper,VoLTE and RCS Technology Evolution & Ecosystem,that offers detailed explanations of both VoLTE and RCS, one riding on the coattails of the other in nearly all cases (See figure). RCS is a business driver; therefore, most operators will choose to deploy it on top of VoLTE to add IP-based messaging as an evolution of Short Message Service (SMS) and Multimedia Messaging Service (MMS), giving their users services such as chat, file transfer, privacy, buddy lists and presence. The paper describes in detail the recommendations and best practices for both VoLTE and RCS implementations and practices.

Source:VoLTE and RCS Technology Evolution & Ecosystem

There are challenges for VoLTE that are being overcome and studied, for example:

Vendors-have their own IMS stack implementations, designs and architecture which presents challenges to portability and roaming

Devices-since 2014, devices typically include VoLTE; this will grow in 2015 but it will take a while for enabled handsets to get seeded into the market and for operators to take their networks live and enable the handset features

Operators-must evolve their legacy messaging services to all-IP IMS-based platforms, often using RCS. They also must address roaming and interworking, such as AT&T and Verizon recently announced as they work together on this important area.

However, the future is a whole new ballgame as operators and users see the exciting home run that VoLTE offers today and has the potential to play out in the years ahead. Just imagine the score when "3D/holigraphic" telephony is available at your fingertips.

For more information, read more VoLTE and RCS Technology Evolution & Ecosystem at 4GAmericas.org.

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