Voice over LTE (VoLTE) is the holy grail for Mobile Operators. It’s the final step in having a single all IP network offering better user experience, greater cost efficiencies and accelerated technology paths. Along with that, it brings a way to tackle existing OTT-type players by providing differentiated Voice Quality of Service (QoS). In fact, most Telecoms-focused conferences and publications talk continually about Voice over LTE (VoLTE): what it is, what it will offer and, more significantly, when it is coming.
If you had read an article on VoLTE last year, most likely it would have talked about the service or technology becoming mainstream sometime within the next 18 months. But to date, very few Mobile Operators have introduced true VoLTE, with the expectation being one or two of the bigger Operators in the US and one or two in Asia Pacific.
So what’s the hold-up?
For most Mobile Operators, and certainly those in Europe, their strategy for Voice over LTE involves continuing to build out their existing UMTS network. In addition, they use techniques such as Circuit Switched Fallback, where the device re-establishes a connection with the legacy 2G/3G network when either making or receiving a call. So why is this?
A lot of the concern is related to cost, not to mention revenues. But there are also issues around Call Continuity. True VoLTE requires not only the LTE access network itself, but also an IMS core network, capable of managing both the call setup and the subsequent media stream. Many Mobile Operators have still to invest in IMS. So for them, at least in the short-medium term, LTE will support Data services only.
Mobile Operators who have IMS already deployed face the issue of what happens when a customer makes a call (over LTE) but then roams out of LTE coverage. In such a situation, the call will simply drop. The only way to avoid that is if they implement techniques such as Single Radio Voice Call Continuity (or SRVCC) which, again via the IMS core, supports the handover of the same call to the legacy 2G/3G and therefore circuit network.
With such considerations for the Mobile Operator, expect the take up of true VoLTE to continue to be slow, at least in the short term. Remember that for many Mobile Operators, Voice is still considered the killer app. It is, therefore, a revenue stream they won’t want to jeopardize, regardless of the technologies they offer.
What are your thoughts on the future of VoLTE? Let me know in the comments below.
To learn more about the challenges of implementing LTE on a large scale, read Minding the Gap: Understanding Customer Experience in LTE Deployments.
Written by Graham Kunz – Graham on Twitter | Posts by Graham
Graham is Empirix’s European Service Assurance Expert and he’s worked in the tech industry for nearly twenty years. More than 14 years of that time has been in Service Assurance, working with wireless customers and internal teams to understand and capture product requirements, as well as develop and introduce products. His global outlook, wireless technology knowledge and technical know-how provide him with an excellent perspective on the current and future direction of mobility and the wireless industry.