VoLTE Wireless Watch

VoLTE – with Optimization huge potential, without Optimization huge risk

Gues Blog from Amdocs by Caroline Gabriel, Research Director, Rethink Technology Research Ltd.

Voice services present mobile operators with significant opportunities, if they are deployed in a way that delivers a strong user experience. Expectations for that experience are rising all the time, so careful optimization of the network is now an absolute necessity for a successful VoLTE project.

The revenues from voice and messaging are falling as over-the-top (OTT) alternatives gain favor, yet the history of data-only cellular services is unencouraging. Moving to IP-based VoLTE can improve the business case by enabling richer services and allowing legacy networks to be switched off, but this is an expensive and time-consuming deployment. That expense needs strong business justifications, and most of these rest on the greater reliability and quality of service (QoS) which VoLTE can provide, compared with either over-the-top alternatives such as Skype and WhatsApp, or with 2G/3G voice. Yet that QoS does not come automatically – it is only achieved when a mobile network is specifically tuned and optimized for the demands of voice, and without that effort, VoLTE presents significant risks to the carrier’s business.

For a QoS-sensitive service like voice (or video calling), the whole network needs to be planned and tweaked to ensure the maximum levels of availability and reliability, so that users experience fewer call drops and higher quality than is typical on an OTT or WiFi alternative. Especially when combined with HD Voice, the differentiation of a superior voice experience is a powerful justification for investing in VoLTE.

It may not be able to charge a premium for voice, which is increasingly offered for ‘free’ in a bundle, but a strong experience will keep users on the network, where they can be monetized. Value added IP-enabled services, such as unified mailboxes and video messaging, can be built around VoLTE to improve the differentiation against OTT solutions as well as legacy, voice-only options. These approaches are particularly important to attract enterprise users, whose need for high quality voice is increasing as many organizations go mobile-first.

So superior quality of experience is essential to make the case for VoLTE – but it is very difficult to deliver, especially when compared to circuit-switched solutions. Not only have operators had many years of experience of optimizing their networks for 2G/3G voice, but the tasks are mainly confined to the RAN. With VoLTE, they are under intense time pressure to launch services quickly, and to achieve high QoS from day one, with a new architecture that requires end-to-end network optimization. That time pressure is a key factor – the original introduction of mobile voice was, of course, an entirely new departure in telecoms, but in the early years, penetration was very low and operators had time to tune their networks. With VoLTE, by contrast, penetration is expected to top 50% of the smartphone base within two years in developed markets.

With a new architecture and this pace of change, new approaches are required to planning and optimizing the services. According to Amdocs’ latest annual ‘State of the RAN’ report, some North American operators experienced significantly more call drops with VoLTE when initially deployed vs. 2G/3G networks which had been optimized over the years. By contrast, some operators in Europe, which had thoroughly optimized their networks prior to launching VoLTE, saw immediate improvements in quality of experience, compared to legacy services.

These contrasting experiences have highlighted the need for service providers to step up RAN optimization during the test and roll-out phases, as well as post-production, to maintain a consistent high quality experience.

Of course, they need to achieve a certain level of LTE coverage to support VoLTE services without fallback to 2G/3G (though some are using VoWiFi as that back-up option). But coverage is only one aspect of the user experience. VoLTE also needs consistent network performance, low latency and unbroken connectivity to deliver on its promises, which requires the RAN to be optimized to a far more demanding level than for most data applications, around specific VoLTE KPIs and a very deep heatmap of voice coverage, call drops and handovers.

Voice over IP may be just another data application, but it is one which makes unique and very stringent demands on the network. Without specific VoLTE optimization strategies, operators face many challenges – particularly to collect and act on network insights from end to end, and across siloes, which is essential to diagnose and prevent problems.

Vodafone Germany launched its nationwide VoLTE service in early 2015 and was rewarded with the best ranking for voice services in the annual Connect-Test survey in Germany ( and also other important Magazines like Computer Bild confirmed Vodafones superior voice service in their test. The company believes that a painstaking process of optimization was essential to go through, before launch – it conducted a year of friendly user trials before it was comfortable to go live and went through a rigorous series of end-to-end network tests, focusing initially on the four basic voice KPIs such as call setup success rate, call drop rate, speech quality and call set-up time, and on SRVCC, before moving on to added value features.

Guido Weissbrich, director network performance Vodafone Germany, says the key to success was “in addition to passion to deliver the best service to our customers, an end-to-end failure analysis and resolution without finger-pointing” with strong cooperation between different network functions within Vodafone, network suppliers and the Amdocs team. From a business case viewpoint, he believes that a strong voice experience does attract customers and support the brand, and it will help Vodafone Germany to migrate all its subscribers, over time, to 4G to free up spectrum in legacy networks. “This is about supporting a premium customer experience rather than specific extra revenue,” he said. “Added value revenue services will follow next, such as PBX integration and fixed/mobile integration.”

Both the largest US operators launched VoLTE later than they had anticipated as they went through the optimization processes, but wisely chose to wait until they had achieved the quality levels they required rather than offer a poor user experience. But those waiting periods can delay the migration from 2G/3G, with impact on the bottom line, and also raise the risk of alienating customers. SK Telecom told last fall’s LTE Voice conference that customer satisfaction with VoLTE had risen from under 60% to 76% after the operator went through a RAN optimization project in 2014, identifying and monitoring key voice KPIs, and prioritizing VoLTE sessions over others.

These are LTE frontrunners, but many other MNOs round the world are now advanced in their 4G roll-outs and are reaching the coverage levels which can support VoLTE. They want to free up spectrum and save operating cost by switching off 2G or 3G, and to generate added value from IP-based voice and messaging. But those attractions must not blind them to the challenges, or to the critical need to optimize the network so that they can deliver a strong VoLTE customer experience from day one. If they do not, they run the risk of damaging their own brand and monetization opportunities, and even of losing customers to rival networks, or to over-the-top services.

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