If there is one technology that could be considered a wild card in 2016, it’s voice over LTE, with an undercard from voice over Wi-Fi. Mobile carriers and vendors have been working on these technologies now for several years, with a number of larger operators having launched VoLTE services, though with little promotion, and VoWi-Fi also becoming a standard option.
However, technical challenges remain significant hurdles to broader VoLTE and VoWi-Fi deployments.
Most still feel VoLTE is inevitable as telecom operators look to streamline their network operations around IP-based technology. This will require carriers to eventually migrate customers from legacy 2G and 3G networks to their LTE deployments. That migration begins with deploying VoLTE capabilities across the network and is followed by the dissemination of VoLTE devices to the customer base.
So far, a number of larger operators have rolled out VoLTE services to their own customer base. Domestically, Verizon Wireless and T-Mobile US claim network-wide access to VoLTE, while AT&T Mobility has been more targeted in its rollout. These inter-carrier initial deployments have allowed for easier monitoring of quality levels and performance surveys have shown solid results.
“There is no question in my mind that VoLTE is superior to 3G voice, [over-the-top] applications and 3G high-definition voice to varying degrees,” said Michael Thelander, founder and CEO of Signals Research Group.
In ranking the overall voice quality experience based on his own testing, Thelander put VoLTE at No. 1; an empty network running an OTT app at No. 2, though with the stipulation that some testing has shown an advantage in this unlikely scenario over VoLTE; a 3G HD voice call at No. 3; and a circuit-switched 3G voice call a “distant” No. 4.
The bigger challenge for VoLTE in 2016 will come as carriers move to expand service interoperability with their rivals. Everyone knows customers need to have a uniform experience with a service regardless of carrier for it to be successful. But, the technology challenge of ensuring service quality has so far marred VoLTE.
“Interconnection is still very complex, and much more so than in a 2G or 3G world,” explained Kevin Riley, VP of engineering and CTO at Sonus. “I think next year we will start to see select interconnection between carriers, but will still be a slow process.”
Verizon Wireless and AT&T Mobility announced in late 2014 they were working on VoLTE interoperability between their networks, with hopes of commercial availability by the end of 2015.
“We know the expectations are high for us from our consumers,” explained Megan Klenzak, AVP for product marketing management at AT&T. “Voice performance is high on their list of expectations and relationship with us. We know it’s important and we are trying to manage to those expectations.”
T-Mobile US has also said it was working with its larger rivals on interoperability, but such a breakthrough remains elusive as the year neared its conclusion.
“We are working with AT&T and Verizon as well on this, though they don’t seem to want to talk about that,” said Grant Castle, VP of engineering services and quality assurance at T-Mobile US. “It’s important and we are working through it. It’s going a lot slower than we would like, but it’s a tall ask. We are not just looking to interoperate with voice calls, but with the whole IMS platform. There is a pretty extensive testing campaign to make sure everything works together.”
Internationally, VoLTE deployments are more diverse. Thelander has spent considerable time in South Korea testing that country’s VoLTE services, which he claims have provided “eye-opening” insight into the technology’s capabilities.
On the other hand, Europe is still seen as to be lagging in broader VoLTE deployments, which has been attributed to generally slower LTE rollouts and a lack of low-band spectrum to support coverage.
“Because of the lack of low-band 4G spectrum deployments in Europe, operators have been more focused on improving 2G and 3G voice services,” said Henry Calvery, head of the GSMA’s Network 2020 program. “The initial LTE deployments have been in the 1.8 or 2.6 GHz bands, which just don’t provide the sort of coverage characteristics needed to support voice services.”
While VoLTE is expected to become a standard offering for mobile operators in 2016, voice over Wi-Fi is a bit trickier. Many mobile operators continue to view Wi-Fi as an offload option only, not wanting to bother working through quality of service issues from the technology’s use of unlicensed spectrum.
The ability to support seamless handoffs between a cellular and Wi-Fi connection remains one of the biggest hurdles mobile operators are facing in terms of truly integrating VoWi-Fi into their product offerings. Even Google, despite all of its resources is currently not able to transfer a call that begins on a cellular connection to a Wi-Fi connection without dropping the call, an affliction that also impacts smaller mobile virtual network operators.
Those issues could begin to be overcome as the year progresses due to growing support of LTE-Unlicensed, which looks to use unlicensed spectrum to help support licensed spectrum-based LTE services.
“One of the variables for voice over Wi-Fi will be LTE-U,” Riley said. “We don’t know necessarily at this point if it plays nice with unlicensed. It may turn out that LTE-U could be an option only for larger enterprises or campus environments where Wi-Fi is more controlled than say something like a Starbucks location.”