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The growth in LTE network deployments around the world has been exceptionally fast, driven primarily by demand for faster data speeds. As of the first quarter of 2014, there were 288 live networks with more than 350 LTE network deployments anticipated by year end. Deployments in North America, Japan and Korea are driving the LTE market.
To date however, voice over LTE deployments have lagged significantly behind LTE rollouts. By 2013, there were more than 30 VoLTE trials underway globally. In 2014, 86% of VoLTE subscribers will be in Asia-Pacific; 10% in North America; and the rest in Europe, the Middle East and Africa. Vodafone, Tele2 and Deutsche Telekom are all trialing VoLTE, and China Mobile, the world’s largest operator by subscribers, is deploying VoLTE on its commercial TD-LTE network in Guangzhou ahead of a planned nationwide rollout. However, if we look at where VoLTE is seeing the most success, we have to look to South Korea.
South Korea was an early leader in deploying LTE networks and quickly achieved high LTE subscriber penetration throughout the country. SK Telekom, KT and LG Uplus followed their LTE success with VoLTE deployments in 2012, minimizing their dependence on circuit switched fall back and single radio voice call continuity. Their subscribers are able to hear the benefit of high-definition audio quality that VoLTE delivers and average revenue per user is up.
South Korea has shown the world the benefits of broad LTE deployment, and increasing ARPU through delivery of VoLTE services. Mobile operators are finally taking steps to implement VoLTE, but turning apathy into action is a relatively new concept for the industry.
There are a number of reasons mobile operators were reluctant to migrate voice services to their LTE networks. First, the delivery of VoLTE requires an IP multimedia subsystem for media processing, which some mobile operators consider costly to purchase and integrate. Rather than invest in an IMS, some mobile operators’ strategy was to keep voice on their 3G networks and use CSFB to support voice for their LTE subscribers.
Second, many operators held a narrow view around the costs and benefits associated with the VoLTE business case. These operators considered mobile voice to be a flat market, and saw all growth opportunities in delivering data. In reality, voice is a $400 billion market and the biggest revenue generator for most operators. Arguably the biggest motivation for deploying VoLTE revolves around spectrum reuse. Mobile operators are already spending billions on “4G” spectrum to grow their LTE networks. By migrating existing mobile voice services to their LTE networks, operators can refarm their 3G spectrum to support LTE network growth. This allows operators to reduce or defer 4G spectrum spending, and frees up funds to cover the cost for installing and integrating an IMS. The benefits of investing in an IMS to deliver VoLTE actually outweigh the necessary costs.
Consolidating mobile networks onto an IP architecture also provides long-term savings. VoLTE not only provides shorter call set-up time than fallback technologies, it also provides a way for operators to meet growing consumer demand for HD voice over a cost-efficient IP network.
Guidance for successful VoLTE deployment
Mobile operators deploying VoLTE should recognize the critical role of the media resource function in an IMS architecture. Many services in an IMS require real-time RTP media processing, including basic VoLTE announcements and digital collections, and value-added services such as multimedia conferencing and real-time mobile video services. The MRF is designed to support all of these service requirements in the network.
Transcoding is also another important VoLTE use case for MRF. While deployments are underway, it will take several years for VoLTE to roll out completely. Therefore the percentage of VoLTE-to-VoLTE calls will be proportionately small, compared to use cases where VoLTE calls need to connect to 3G, PSTN or even WebRTC endpoints. Mobile operators will need to transcode VoLTE AMR-WB codec to AMR-NB (used in 3G) or other PSTN codecs. These transcoding use cases will require significant MRF processing power in the IMS Core. Video transcoding and transrating will also continue to grow in volumes, requiring even more transcoding power.
Mobile operators that integrate an IMS for VoLTE can also offer differentiated revenue-generating services, such as RCS, multimedia conferencing, Video RBT and multi-mode messaging to both SIP and WebRTC endpoints. In addition, by leveraging a common MRF to deploy these services, mobile operators can also achieve scale economies. And by adding end-to-end network visibility through service-aware policy control to improving quality of service, mobile network operators can further differentiate their integrated mobile communications offerings against OTT alternatives that don’t own the network, and consequently can’t control the end-to-end network experience.
A growing area of interest for mobile operators is deployment of an IMS based on network function virtualization technologies. Operators can leverage virtualized media processing today for their VoLTE deployments. We recently covered this topic in an RCR Wireless Hangout on “Media Processing in the Cloud.” However, some applications such as large scale transcoding or video may still require purpose-built media processing resources. Operators should work with MRF vendors that offer both hardware and virtualized solutions, to maximize their flexibility around future growth strategies.
Mobile operators are increasingly recognizing the long-term benefits of supporting VoLTE and acknowledging that an IMS is a strategic investment, not a waste of time and money. LTE networks with an IMS-based strategy provide significant cost, technical and operational benefits. By embracing VoLTE, mobile operators can differentiate their services against OTT competitors and increase ARPU. We’re happy to see apathy finally turn to action.
Ray Adensamer has worked in the telecommunications industry with industry leaders including Convedia (now Radisys), Abatis (now Redback) and Nortel, along with system integration firms Deloitte Consulting and Accenture. He enjoys sharing his passion and viewpoints around IP-based telecommunication solutions with Radisys customers and partners. Adensamer has a B.A.Sc. in Systems Engineering from the University of Waterloo along with an M.B.A. from the University of British Columbia.
