VoLTE versus VoIP

Author: Ricardo Tavares
Published: 2014-10-27

Over the coming years mobile operators around the world are going to see a major shift in their business models thanks to the introduction of voice over LTE (VoLTE).

To some extent VoLTE has crept in under the radar, despite the influential GSMA having launched a VoLTE initiative to promote “the industry-agreed progression of voice services” and ensure international uniformity in its implementation.

The benefits of VoLTE to both carriers and subscribers are many, but will not be fully realized until carriers have the same population coverage on their LTE networks as 2G and 3G, and probably until they have introduced LTE Advanced (3GPP Release 10 and above).

The handful of carriers who jumped the gun on VoLTE before coverage, technology and ecosystems were ready found it difficult to get the service up and running. Via circuit-switched fallback technology (CSFB), VoLTE customers also had to be dropped to 2G/3G when out of LTE signal range losing their data stream in the process.

The advantages of VoLTE for the subscriber include high definition (HD) voice and video calling, simultaneous voice calls and data sessions – allowing the sharing of photos and videos while talking – and transforming voicemail to a converged multi-device, multi-account service with advanced features such as videomail. In other words it is a very different beast to VoIP.

For the operator it means far more efficient use of spectrum than 3G switched-circuit voice (some operators claim by a factor of three), and, once full coverage is achieved, the ability to switch off 2G and 3G networks and refarm the spectrum for 4G (employing carrier aggregation for more bandwidth and faster speeds).

It also means operators can finally fight back against free or cheap, but poor quality, OTT voice and messaging providers by offering reasonably-priced, crystal-clear voice and video calls, and enhanced messaging services, with a guaranteed quality of service (QoS).

VoLTE is enabled by having a Multimedia Core Network Subsystem (IMS) as part of an all-IP network. IMS has been around for several years (first specified in 3GPP Release 5) and some operators like NTT DoCoMo introduced it on HSPA networks, but it is really coming into its own alongside LTE-A.

Its deployment is following the pattern of LTE deployment, and particularly LTE-A deployment, with the first mass adopters being the three Korean operators, and other Asian operators in Hong Kong, Singapore and Japan. China Mobile has just begun a nationwide rollout. In the US, T-Mobile was an early adopter but Verizon and AT&T are now launching their nationwide services.

In the EU all the major operators are conducting, or soon to conduct trials as they bring LTE-A and carrier aggregation online, and Du of the UAE has become the first operator in the Middle East to launch VoLTE.

And providing a vision of the future, South Korea’s LG U+ is the first operator in the world to turn off its 2G and 3G networks and go all-4G with VoLTE as its only voice service.

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