VoLTE and WiFi Calling : In holy matrimony against OTT ?


Across mobile networks deploying LTE radio access technology, Voice over Long Term Evolution (VoLTE) and Video calls over LTE which utilise IMS technology are recognised as the industry-agreed progression of voice services. VoLTE facilitates far richer, multi-media voice services, increasing the service quality (by offering HD Voice) and interest delivered to consumers.Concurrently with the increasing prevalence of Wi-Fi access networks and the change in attitudes relating to Wi-Fi as complementary RAT and the proliferation of Wi-Fi Calling enabled devices, the time to deploy feature rich alternative voice services has never been more favorable for Telcos.

According to the GSMA, in July 2015 422 operators deployed LTE networks in 143 countries. As the roll-out momentum continues VoLTE, which utilizes IP Multimedia Subsystem (IMS) technology, is recognized as the industry standard agreed progression of delivering voice services in a packet switch only network.The size of the VoLTE market will be over $30 billion through 2019, says ABI Research. Visiongain expects there to be 101.7 million active VoLTE subscriptions worldwide by the end of 2015. Apple’s embrace of VoLTE with the iPhone 6 raises the bar and points the way for all device manufacturers to follow. ABI Research believes that VoLTE subscriptions will significantly increase year-on-year as subscribers appreciate the voice quality and demand the additional services of the all-IP 4G LTE.

So why the hoopla over VoLTE and WiFi calling ?

For starters a VoLTE network has up to 3 times more voice and data capacity than 3G UMTS — and up to 6 times more than 2G GSM — and that extra capacity helps you sell more data services. To sweeten the deal VoLTE’s packet headers are smaller than unoptimized VoIP/LTE, so that more bandwidth is available for data services. For instance, in a cell with 200 VoLTE calls, 4.4 Mbps is freed up for data services. VoLTE also reduces the consumption of each cell’s control channels, so the cell can serve more users and increase throughput for non-voice data services.As VoLTE would use substantially fewer network resources than say Skype voice, which in turn results in longer estimated device battery life for the subscriber and a more efficient network for the operator.

Telcos in developed markets see VoLTE as both a means to gain competitive advantage over rival service providers and a tool to bolster their brand strength. VoLTE promises operators will be able to fully utilise their IMS infrastructure investments, optimise their spectrum efficiency, and add value to existing voice plans.As the developed markets begin to move towards comprehensive LTE coverage, VoLTE will no doubt become an integral part of network architecture .

Vodafone announced recently that it aims to get both its VoLTE and WiFi calling infrastructures up and running by this summer.With the launch of Wi-Fi Calling and VoLTE, CSPs have a good opportunity to win back their customer’s voice usage from OTT VoIP providers. VoLTE and Wi-Fi Calling have a key differentiator compared to OTT players in that they can use a native dialer. Customers make calls and texts as if they are using the cellular network i.e. they use the phone’s normal dialer and contacts. There is no need for an app, and your contacts don’t need to be using closed user group services to talk to or message each other. As the range of VoLTE and Wi-Fi Calling enabled handsets continues to expand, these advanced voice services give Telcos a better foundation to win back customers’ voice usage from OTTs.

WiFi calling should help let users make calls in places where cellular signal is weak or non-existent, sending your voice over a WiFi network instead. It won’t reap the same benefits as VoLTE when it comes to power efficiency, but it’ll keep people connected in more places.Some of us might be already be familiar with the concept, whether using Skype or carrier’s offerings like Three’s InTouch app. Either way WiFi calling will negate the need for an additional app, letting you make a take calls from the dialler as you would with a conventional cellular call. Vodafone’s offering an approximate launch date of summer 2015, whilst the ability to use VoLTE also depends on the phone’s hardware. A number of top new Android handsets along with the latest pair of iPhones support VoLTE, but it’ll take a little while for the technology to trickle down to more affordable handset.

AT&T in the US is an example of an operator that deployed VoLTE ahead of Wi-Fi Calling.Initially launched in July 2014, AT&T continues to bring VoLTE to more states in the US with an ongoing rollout plan. The operator is expected to launch Wi-Fi Calling by the end of 2015. Many CSPs are starting with VoLTE over Wi-Fi Calling to avail of improved efficiencies over 3G. LTE offers twice the spectral efficiency of 3G/HSPA and more than 6 times the efficiency of the GSM technology. This improved spectral efficiency makes it possible for VoLTE to handle twice as many calls, helping to optimize the use of radio resources and reduce costs. The requirement to migrate circuit switch voice traffic onto VoLTE is also a deciding factor for deploying VoLTE in advance of Wi-Fi Calling.

T-Mobile US made a big splash in the market in late 2014 when they heavily promoted their Wi-Fi Calling service to overcome any coverage issues. To drive adoption of the service, T-Mobile allowed customers to upgrade to a new Wi-Fi capable smartphone at no additional cost. In addition, T-Mobile offered a free proprietary “Cellspot” Wi-Fi router (to all Simple Choice postpaid customers to enhance their in-home coverage). In Q1 2015 T-Mobile reported that 7 million customers were using Wi-Fi Calling. T-Mobile also reported that over 10 percent of voice calls run on its new Voice over LTE technology. The operator expects growth to accelerate significantly and notes handset adoption as the key enabler to success.

When delivering voice services, Telcos need to consider latency, loss, and jitter, which would not normally be associated with many data services. They must ensure that the LTE coverage and Wi-Fi hotspots, accessed by customers to make voice calls, have sufficient coverage to deliver an acceptable Quality of Service (QoS). In relation to VoLTE calls, the challenge lies in being able to dedicate sufficient resources to guarantee the quality of the call. A Policy Control Rules Function (PCRF) is required to define the QoS for the call. This is possible as the CSP has visibility of the QoS from the user’s device to the network. The PCRF initiates the creation of a dedicated bearer that carries the voice traffic for the duration of the call. It also guarantees bit-rate for voice data.

T-Mobile Czech Republic has become the first operator in the country to launch Voice over LTE (VoLTE) commercially. VoLTE allows standard IP calls on LTE networks.The first supported device is the Samsung Galaxy S5. T-Mobile is working intensively to offer new models, in cooperation with manufacturers.The biggest advantages of VoLTE is a very short time for call set-up, enhanced quality of call (even compared with HD Voice in 3G) and lower energy consumption per call, or a longer battery life. During the call, there are no restrictions on data connections, e.g. simultaneous use of online navigation and calls when driving a car. When a user leaves the area of LTE coverage, the call is handed over to a 2G or 3G network (function SRVCC). Customers will get notifications requiring them to update their firmware.T-Mobile will subsequently deploy VoLTE automatically to clients on their current telephone numbers. In order to properly monetize VoLTE services, Telcos do need functions of an online charging system sitting in the BSS/OSS so that VoLTE and Wi-Fi calls can be billed in the same way as traditional voice.

Swiss operator Salt launched Wi-Fi Calling in June 2015. Salt states that Wi-Fi Calling turns every Wi-Fi router into a Salt antenna. They reference over 3,000,000 Wi-Fi hotspots available which include those of their competitors (Wi-Fi router Swisscom, Sunrise, UPC Cablecom at home etc. and all public Wi-Fi hotspots). In July 2015, Salt extended their Wi-Fi Calling initiative to include Wi-Fi Calling worldwide, making it one of the first operators in the world to offer this service. The initiative will abolish roaming costs for Salt customers, with all calls and SMSs charged according to the applicable subscription – so its always as if you are making your call in Switzerland.

Ofcourse it makes no difference to customers whether the call is made over the cellular or Wi-Fi network provided the quality is satisfactory.With fierce competition within the industry and poor coverage ranking as a key driver for customer churn, QoS management should and must be at the forefront of VoLTE and Wi-Fi Calling roll-out strategies for all Telcos.The bane of OTT VOIP is poor QoS and dropped calls..and that is why VoLTE + WiFi Calling is a golden opportunity for Telcos to claw back some of what they have lost to OTT’s.

Sadiq Malik ( Telco Strategist )


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