Michele Zarri, head of international standardisation and IP management, Deutsche Telekom, UK is speaking on Day One of inaugural LTE Voice Summit, taking place on October 1st-2nd at the Hilton Paddington, London. Ahead of the show we get an update on Deutsche Telekom’s progress on VoLTE.

When we spoke in May you said that consumers will use VoLTE as they prefer telco quality voice services? With OTT voice set to grow massively over the next 12 months will consumers really care about VoLTE?

I respectfully disagree with the notion that OTT voice is set for a major growth. Though LTE will greatly improve bandwidth and latency, current HSPA and WLAN access is perfectly capable of supporting OTT voice. As smartphone penetration for which many OTT voice clients exist is already significant, there therefore seems to be not much reason why customers should suddenly change their habits. OTT will grow because the general trend of voice traffic is growing, but I still see OTT voice as a different product than VoLTE and catering for different use cases.

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Will VoLTE only make sense once you have blanket LTE coverage?

As long as we restrict ourselves to the basic voice service, thanks to the mechanisms that have been specified by 3GPP, it is possible to use legacy technologies without significant loss of quality, and potentially none at all if HSPA is the fallback radio technology. Though LTE coverage is desirable to allow multiple data connections in parallel to voice as well as multimedia telephony, there is no need to wait for blanket LTE coverage prior to launching LTE voice.

What is the greatest benefit of VoLTE to operators? Is it lowering cost per bit, or something else?

Of course the voice production cost is believed to be lower than the current CS voice, but more importantly, VoLTE is a fundamental stepping stone towards the migration towards a full packet switched network. At present mobile operators have to maintain two domains, which implies complexity as well as inefficient use of the expensive spectrum where operators run their circuit switched services. Although the migration to a pure packet-switched network is still several years away, such a transition would be unthinkable without the capability of offering voice over packet-switched.

What is the biggest technical challenge in implementing VoLTE?

As a ‘flavour’ of the more generic voice over IMS, VoLTE does have strong dependency on IMS. However, this is not the major obstacle since many operators have already successfully deployed IMS in order to launch Joyn and some operators can also rely on the wealth of experience gained from the deployment of IMS in fixed networks.

I would say however, that there are two challenges that the industry will need to address for a successful deployment of VoLTE.

Firstly, there is terminal compliance. Though the GSMA did a great job in profiling a terminal supporting voice over IMS and SMS, based on historical data, we can expect some degree of divergence in the behaviour of terminals. As of today there is no certification program in place and that puts the onus on mobile operators to perform extensive device testing, which may result in delays.

Secondly there is seamless migration. As discussed above, with simplicity at its heart it is the aim of Deutsche Telekom to shield subscribers from the complexity of providing the same user experience when moving to voice over IMS. Achieving this goal requires quite a lot of work behind the scenes, for example, with regards to supplementary services support and things such as back office systems. To paraphrase a famous quote from Tomasi de Lampedusa, “a lot of things will have to change for things to remain the same”.

Could a combination of VoLTE and Joyn be monetised and keep users away from OTT?

The use of VoLTE as the voice component of the Rich Communication Services is already in the roadmap as it would be wasteful in terms of resources and confusing for the customer to offer many ways to enjoy the voice service. There are still some hurdles to overcome towards the integration of VoLTE and Joyn, particularly in the area of international roaming, but once these difficulties have been ironed out, mobile operators will be able to offer a service with at least the same capabilities offered by any of the current OTT providers with significant additional advantages such as integration of the client, security, privacy protection, trusted charging relationship, better access to network resources (i.e. QoS) and so on.

As for keeping users away from OTT, as I stated above, it is Deutsche Telekom’s opinion that these are two distinct products. As in every other market consumers will have the freedom to choose the product more suitable for their needs. As an example, consider the automotive industry: the fundamental service that a car offers is going from A to B, this however has not stopped competition and the proliferation of segments, each responding to a specific type of customer. I can see the same happening in the voice communication area.

What are you most looking forward to about attending the Voice over LTE conference?

I really hope that the conference will be an opportunity to dispel the myths of the non-readiness and non-viability of VoLTE. From its inception VoLTE has faced harsh criticism, first in the form of VOLGA, then CSFB and OTT. This is not surprising given the novelty of the technology, however I believe that we are now in sight of the finish line and I hope the conference will reinforce my belief that VoLTE is happening.