Bhaskar Agastya, Country Manager, Sales, Ixia India

Voice over long term evolution (VoLTE), touted as the next genera­ti­on of wireless communication techn­o­logy, is helping expedite the mobile internet evolution. The application of VoLTE offers many benefits, in terms of both cost and operation. It delivers a more proficient use of spectrum than traditional voice. Additi­­o­nally, it helps meet the growing demand for richer, more reliable services.

VoLTE is a technology implemented by many operators world over. It is one of the first services to fully leverage end-to-end quality of service (QoS) capabilities built into IP multimedia system (IMS)-based LTE networks. Operators can market and monetise this advantage by making deals with over-the-top (OTT) providers seeking to differentiate on quality and by rolling out their own premium services to generate new revenues. By fully leveraging IMS and the QoS mechanisms inherent in LTE, VoLTE supports HD voice as well as services based on guaranteed quality. The question is: how much will customers pay for it? Services like Skype, Facebook, Whats­­App and Fring have been wildly popular. They have introduced functionality and novelty at virtually no cost. But history has shown that users will pay for real-time services like GoToMeeting and Microsoft Lync to ensure higher quality and security. Business customers, in particular, still shy away from any free or low-cost service that delivers a less-than-satisfactory experience, and may be inclined to pay a premium to bolster their own customer service.

To offset revenue loss to OTT services, operators have two viable options – they can partner with or sell to an OTT provider seeking differentiation or launch compelling paid services that let customers do something more, better, or cheaper. OTT providers that cannot guarantee service quality on their own may do well to pay to leverage it.

Currently, Reliance Jio is the only operator in India offering voice on 4G network using VoLTE technology, while other operators have been offering voice calls to their 4G customers with the support of their other established networks – 2G and 3G. The roll-out of VoLTE by larger players is expected to open up a new frontier in the price war and experts say it may set the stage for cheaper voice offerings. According to the Ericsson Mobility report, India’s VoLTE subscriptions will touch 370 million by 2022, and the global base will reach 4.6 billion in the same period. And it is not just about voice. With the growth in data traffic, the VoLTE subscription is expected to grow at around 40 per cent annually and reach 8 exabytes of data by 2022.

Challenges in deploying VoLTE

The “flip side” of being able to deliver voice and data over one network is that those networks must now be optimised for both voice and data. Delivering high quality voice is more challenging and doing so in the form of data packets, even more so. Apart from the sheer novelty of this undertaking, VoLTE involves lots of new moving pieces, unproven technologies and interdependencies. Major challenges in ensuring successful deployments out of the gate include validating new devices and configurations, interoperability in increasingly multi-vendor environments, signalling, ensuring quality of experience (QoE) and scalability. Not just that, the emergence of VoLTE-capable devices is raising new security concerns for mobile network operators, as existing IMS dep­loy­ments expose vulnerabilities in VoLTE handsets to other devices in the network. Some of these vulnerabilities are new and not previously disclosed: they may allow an attacker to silently retrieve private pieces of information on targeted subscribers, such as their geolocation.

Validating VoLTE

To date, service providers worldwide have relied heavily on equipment manufacturers to validate the performance of both their own devices and overall network designs. Today, in the face of steadily rising traffic volumes and expectations for quality, this approach is far too risky. Most operators’ networks increasingly consist of equipment from multiple vendors. And obviously, each network is unique such that operators need to test their specific configurations, services and traffic mixes to find potential issues and bottlenecks. With so many new and moving pieces involved, ensuring a high quality VoLTE roll-out requires end-to-end validation that begins in the lab and continues into the live network. Life cycle validation strategies are needed and should include design, planning and device selection, prototyping services, visibility monitoring, problem resolution and critical test capabilities.

VoLTE testing should focus on end-to-end service validation rather than individual device (node) testing. Network operators do not need to duplicate their vendors’ development testing, but rather measure the expected user experience. To do this effectively, testing must be performed with all the components that will be used in the live network. Since maintaining a lab-based replica of the entire live network is not practical or cost-effective, purpose-built test systems can be used much more cost-effectively.

In general, a VoLTE test system must support functional, performance and stability testing of session initiation protocol (SIP)-based VoIP network components as well as a wide mix of voice, video and data applications. Using an automated, repeatable and proven approach enables operators to assess the impact of each decision they make on device and network performance, as well as the ultimate quality of experience delivered. Validation strategies and test methodologies should include several critical components and capabilities.