By Gunmeet Singh Nagpal, Associate Director – Product Management at Mobileum
VoLTE (Voice over LTE) is the latest iteration of the progression of voice services across mobile networks. VoLTE offers quite a few advantages over 2G/3G voice, mainly due to superior voice quality, faster call connectivity, improved battery life, and support for video calling.
The History of VoLTE
Initially, most operators designed their LTE network to support (non-voice) data services, with voice calls remaining on their 3G network. This was done to launch LTE more quickly and with minimal cost. That is because VoLTE requires additional investments into the IMS core.
Today there are approximately 729 networks that support LTE – yet only about 188 of them support VoLTE1. But that trend is changing.
According to a leading industry report, VoLTE subscriptions are expected to reach 5.9 billion by 20242. Close to 50 operators worldwide have announced the closure of their 3G Networks, and many more are expected to follow in the coming months and years, transforming them to pure LTE network making VoLTE mandatory for voice.
This transition to ‘all-IP’ creates operational efficiencies for wireless MNOs because they no longer need to invest in supporting multiple networks- and it frees up additional spectrum, improving utilization for upcoming 5G networks on the horizon. With 2G and 3G networks falling by the wayside, VoLTE suddenly becomes mandatory if a MNO wants to continue to offer voice services – and most certainly do.
We live in a world where people travel the globe and still expect to be connected - wherever they go. With voice services transitioning to VoLTE, there is of course still a need for MNOs to provide roaming services. But what does this mean for MNOs and their roaming partners?
VoLTE Roaming – Are you ready?
Globally, there are fewer than thirty commercial VoLTE roaming agreements in effect today. Soon though, many mobile network operators will be launching VoLTE domestically, making them technically ready to support VoLTE roaming.
Our research shows there have been four key reasons for this low adoption rate:
- Technical challenges: VoLTE calls, from a technology perspective, are very different than traditional 3G calls, which impacts current rules and regulations around Lawful Interception (LI) and Emergency Calling services.
The GSMA has already resolved the key technical challenges related to lawful intercept and emergency calling. This is giving operators greater confidence to establish support for VoLTE roaming.
- Financial implications: Under VoLTE, voice services are billed not as minutes of use - but bytes of data consumed. Operators are not sure how this will impact their revenue and cost.
There are models available now to address uncertainty on the positive or negative impacts of implementing VoLTE roaming. GSMA also provides assistance for these models.
- Network hurdles: Change takes time. Many LTE MNOs without IMS core, still rely on legacy networks that can’t support VoLTE for their roaming subscribers.
More and more operators are investing in VoLTE by implementing the IMS core. VoLTE is one of the key priority for many operators as this will enable them to offer better user experience to their subscribers for voice calls.
- Lack of urgency: Because MNOs have been able to rely on 3G network as a fallback for voice services while roaming, there is less urgency to provide VoLTE as an alternative.
This attitude has shifted. Many mobile operators are already shutting down their 3G networks, and many more are planning to do the same in the near future. There is now a growing sense of urgency to establish VoLTE roaming capabilities - or risk subscribers losing access to voice services while traveling. MNOs need to ensure that all existing VAS (Value Added Service) solutions are also migrated to VoLTE, to ensure a seamless experience for their roamers. VoLTE roaming also makes commercial sense - as many pure LTE networks are offering very competitive wholesale rates to acquire VoLTE in-roamers, helping MNOs reduce costs and increase margins.
MNOs need to gear up their steering platforms to ensure that only VoLTE subscribers with the right handsets are steered to pure LTE networks, while others subscriber are kept on 3G networks. This is required to ensure roamers receive uninterrupted voice services, while also ensuring wholesale costs are optimized.
With VoLTE, all call controls reside at the home IMS core, so theoretically the TAS (Telephony Application Server) can perform most of the required policy control functions. Typically, TAS is not overloaded with multiple roaming related use cases, like shortcode translations and call corrections, which are VPMN-specific. Also, MNOs need to ensure that their TAS node, and other complementary solutions, are geared up for other roaming related use cases like fraudulent call blocking, fair usage policies, bill shock notifications, and fraud prevention. These policies are typically dependent on the visited location.
To ensure quality of service while roaming, quality monitoring platforms need to be enhanced to monitor VoLTE KPIs such as Voice Call Establishment, Accessibility, Retainability and Speech Quality.
Like any other roaming agreement, setting up VoLTE roaming agreements can be expensive (both in terms of cost and manpower), and time consuming. MNOs may prefer to outsource their VoLTE roaming testing, either partially or completely. From a performance and resource perspective, MNOs should also look at automating VoLTE roaming testing as much as possible, rather than doing it manually.
One Step Ahead on the Path to 5G
5G networks are about to be launched, and this is already having an indirect impact on the mobile operator’s adoption rate of VoLTE. With 5G (Standalone Mode), there is no support or fallback to circuit switched voice calls. The IMS core is a mandatory requirement. Moving to IMS for voice services today will provide operators with an easier path to 5G tomorrow.
For more information on VoLTE roaming and how we can help, contact us today.
1 GSA : VoLTE Status Worldwide – May 2019
2 Ericsson Mobility Report – May 2019