forcing vendors to enter a cat-and-mouse game

Voice is Coming to LTE

[Post is better viewed on the blog Website]

 Back in 1999, when 3G was still a questionable dream, IMS started to take root as an architecture for mobile services. It was adopted by the 3GPP and later on also by 3GPP2 and other organizations and forums. Standardization work went on for many years resulting in continuous releases of standard versions forcing vendors to enter a cat-and-mouse game.

forcing vendors to enter a cat-and-mouse game

The adoption of IMS was slow and disappointing

There are many IMS deployments today but IMS didn’t deliver on its promise. While vendors and service providers were busy fighting in the standard bodies, small start-ups came quickly to the market with advanced services and took the market by storm.

VoLTE is based on IMS and is defined in IR.92 and IR.94. In a nutshell, it defines Voice, SMS over IMS (IR.92) and Video (IR.94) over LTE networks.

So what is all the fuss about VoLTE?

The answer to that lies in the eyes of the beholder.

LTE networks are being deployed by hundreds of service providers worldwide. Once LTE coverage is ubiquitous, there is a lot of sense for the service provider to move away from circuit switched (CS) voice to VoLTE, as in a few years it will eliminate the need to continue supporting the CS network, thereby reducing OPEX.

Additionally, higher quality end-to-end voice will be possible as VoLTE supports HD voice and includes features for resource reservation as well as other important features such as security.

From the end user perspective, in addition to the higher quality voice and security that comes with VoLTE, longer battery life will be possible as the need for dual LTE & CS connectivity of the phone will be removed.

Reality check

Learning from the past, there are 3 fundamental challenges service providers and vendors will need to solve.

Time to market

Service providers have waited for technologies to become stable and for standards to become fully ratified. This stopped them from launching advanced services, leaving the door open for OTTs.


The reality is that service providers currently providing VoLTE services are not all doing so the same way. Different capabilities and scenarios are supported by each service provider. This results in the need to verify each device and server before it is deployed on their network and vendors are required to make modifications in order to pass this certification process. Given this reality, there is a need to have a mediation element (SBC) between service providers, thus interoperability is theoretical… (did I say there is no point in waiting for everything to be perfectly compatible and ready?) Launch…don’t wait.

There are other networks out there

The service provider world is more complex than that of an OTT. The service provider doesn’t have the benefit of building an island. It needs to connect to older networks, enterprise networks and other service providers. This again brings up the need for that demarcation point that will mediate signalling and make sure voice quality between those networks remain good.

Speaking with service providers that are already invested in VoLTE and interconnecting with other networks, voice quality and QoE are their main concerns. Solutions for these concerns are provided through advanced audio processing done in mediation entities that interconnect between the networks.

Stay tuned for more on QoE in future posts on this blog.

Why is this important?

There are different opinions about the future of VoLTE and its chances to succeed. There is no doubt that secured voice calls using HD codecs are possible today using OTT. It is also clear that an OTT will not go this route, but in the service provider space VoLTE looks like a technology that will happen because:

  • It makes sense from an operational cost perspective
  • VoLTE integrates nicely into the service provider’s existing OSS/BSS systems
  • There are ways to downgrade the call to 3G/TDM when LTE is not available…SRVCC

Having said that, interoperability is a challenge. Service providers should assume there will be no 100% interoperability and standard support both on phones and servers. Certification of clients will always be required as well as demarcation points between networks as exist today in their VoIP networks.

Therefore time to market is more important than completing every item on the standards checklist.

2 replies
  1. Paul E. Jones says:

    Amir, you said that “once LTE coverage is ubiquitous” that service providers will move away from circuit switched. It doesn’t really have to be ubiquitous. Service providers can do that immediately within their own network. Peering between service providers is already via VoIP in most cases, so this will not be a huge leap.

    It is in the service provider’s best interest to make the move, as otherwise they’re consuming valuable wireless spectrum to support legacy voice service. Given that voice service is really not a big money maker in many developed countries, there is definitely a desire to free that spectrum for data services.

    I do personally think VoLTE will be successful for only one reason: to allow a move to LTE and free spectrum. This is not a move to make money from voice, but a move to save money on costly legacy technology and wasted spectrum.

    Service providers will continue to face new and interesting OTT players. That’s actually great! When carriers ask me how to deal with these companies (i.e., “how can we make money?”), my standard answer is “become an OTT company!” Seriously, what service providers need to do is innovate. There is nothing really for them to innovate around vanilla voice or video services. There are plenty of OTT services that do that and for carriers to compete would be a disaster for the carrier. What carriers should do is invest in these kinds of companies. I would say carriers should buy companies like WeChat or WhatsApp, but (dare I say) they’d likely ruin those companies. So rather than do that, carriers should either just invest _or_ acquire them with the intent that they will remain a wholly-owned subsidiary that operates autonomously and is rewarded for success.

    This is the new reality. Whereas charges for voice minutes is what made carriers a lot of money in the past, that’s no longer the case. Consumers are talking less and user a variety of data services a lot more, including chat, music, taxi hailing services, streaming video, etc.

    What I do not know is what regulatory tape bounds carriers. If there is any, though, they need to work to get rid of it so they can continue to expand their businesses in areas outside of traditional voice services.

    • Amir Zmora says:

      Hi Paul,

      When saying “Once LTE coverage is ubiquitous” I’m referring to the fact that once a service provider has LTE coverage he can move away from circuit switched. That is within their own network as you commented.
      I fully agree with your comment about cost saving, that is part of what the post was trying to convey – “as in a few years it will eliminate the need to continue supporting the CS network, thereby reducing OPEX.”
      To my view, cost saving is one of the key reasons for VoLTE to really happen (I guess we are on the same page here).

      With regards to OTT services. We need to remember that OTT is free or fermium. A problem for service providers.
      I fully agree with the need for service providers to provide advanced services and that best is to do that in OTT mode. The thing is that it impacts their business models and therefore the value for service providers from OTT is user stickiness and services targeted at specific segments. Well, I guess that will need to be covered in more details in a dedicated post.



Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *

Captcha * Time limit exceeded. Please complete the captcha once again.