LTE Voice Lag Leaves Operators Vulnerable

The longer mobile operators delay offering their own voice services over Long Term Evolution (LTE), the more vulnerable they could be to over-the-top (OTT) voice over IP (VoIP) service providers, finds a recent Heavy Reading Insider report.

Operators are not in a hurry to deliver voice services over LTE networks, says Robert Poe, author of the Heavy Reading 4G/LTE Insider report, "Voice Over LTE: More Pitfalls Than Promise for Now." This is because they can use their 3G or 2G networks to deliver voice services, reserving the packet-based LTE network for data services, a technique called "circuit-switched fallback." (See LTE TDD: In Mobile, Size Matters.)

But if operators wait too long, they could face some negative consequences. (See Google Gives Telcos a Wakeup Call.)

"The main one is that over-the-top VoIP providers -- like Skype Ltd. , fringland Ltd. , and Nimbuzz Group -- could offer voice services over the speedy new LTE connections," says Poe, adding that such services represent a significant threat to operators' existing voice revenues because they would probably be cheaper and could even offer better quality with high-definition voice technology.

"So the period in which operators have deployed LTE networks but are not delivering voice services over them represents a window of vulnerability for them," says Poe.

One operator facing that window of vulnerability is Telia Company , with its commercial LTE networks in Norway and Sweden. The operator's CTO of mobility services, Lars Klasson, told Light Reading Mobile in a recent interview, "We're not in a rush to put voice onto the 4G networks."

But when the Swedish operator is ready to put voice over its LTE networks, it will use IP Multimedia Subsystem (IMS)-based VoIP, Klasson said. (See TeliaSonera First to Go Live With LTE.)

However, over-the-top VoIP doesn't have to be a threat to mobile operators. It's possible for operators to use these services to their advantage, finds the Heavy Reading report, either by offering their own over-the-top VoIP services, or by partnering with VoIP service providers.

The IMS dilemma
The standards-based way to deliver voice services over LTE is to use an IMS architecture in the network, an option driven by the One Voice industry initiative and which became the 3rd Generation Partnership Project (3GPP) 's voice over LTE (VoLTE) specification.

But, according to the report, there is a disconnect between IMS and LTE deployments. Operators are deploying IMS and LTE independently, so the technologies may not be rolled out at the same time or in the same place. (See Operators Rally Round IMS for LTE Voice and Voice Over LTE & the 'IMS Gap'.)

This situation has had two results: First, there will be a need for alternatives to IMS-based LTE voice services; and second, there has been an acceleration of some operators' IMS plans specifically to enable LTE voice services.

The alternative approaches for LTE voice services include circuit-switched fallback, VoLGA (voice over LTE via generic access), Nokia Networks 's fast-track VoLTE, and over-the-top VoIP. (See New Specs Deepen LTE Voice Dilemma, NSN Goes Solo for LTE Voice, and T-Mobile: Voice Discord Threatens LTE.)

— Michelle Donegan, European Editor, Light Reading Mobile

ingenieur 12/5/2012 | 5:05:36 PM
re: LTE Voice Lag Leaves Operators Vulnerable

in the near future, i believe most people will have one phone for voice over 2G/3G, and one LTE phone for data service until one phone can do both one day.

Michelle Donegan 12/5/2012 | 5:05:35 PM
re: LTE Voice Lag Leaves Operators Vulnerable

I think so too. Even with phones that support both 3G and LTE, there is still a problem in the network with handover between the two networks.

NetworkOptimizer 12/5/2012 | 4:21:22 PM
re: LTE Voice Lag Leaves Operators Vulnerable

The first generation of LTE phones that is coming out has single receiver. So, if you are using it for data on LTE, you cannot use it for voice on 3G/2G.

I think this is a big drawback, especially since AT&T has sold this feature with a very good marketing pitch.

IMS is too complicated and expensive to deploy.

It's going to be interesting to see who wins in voice over LTE. No one wants to commit. If a greenfield LTE deployment offers both and markets it well, it will force others to follow.

wfoster8560 12/5/2012 | 4:21:17 PM
re: LTE Voice Lag Leaves Operators Vulnerable

I was surprised that the article in talking about LTE and IMS did not discuss the value of VCC (Voice Call Continuity) that is part of the IMS spec and which can be used for guaranteeing quality of service when switching within and between networks.

Users may be willing to pay for QofS (Quality of Service) both for  voice and for more video hungry applications such as high definition video, holographs, etc.

Imagagine the demand on the global switching framework if the world moves to LTE with its 1 Gbps up and downstream speeds.  Vulnerable points will be the Internet exchanges and also the International fiber.  The IMS standard needs to be extended so that applications can negotiate through an auction mechanism with the network for how much speed and QofS they are willing to pay for.

William Abbott Foster, PhD

Faculty Associate

Arizona State University


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