FUTURE OF VOICE SPECIAL REPORT: LTE roaming: The rise of a roaming empire

The growth of LTE roaming surpassed all expectations in 2014. The market looks set to soar further in 2015, but with VoLTE looming fast, operators face some tricky decisions.

Growth in LTE subscriptions is effortlessly exceeding that of all other mobile technology. Research firm Ovum says that LTE adoption outstripped 3G on a worldwide basis by 21% for the last six months of 2014, and it is now powering the mobile lives of around half a billion end users. It took 3G several years to achieve that milestone.

But while LTE is by most reckonings the most exciting thing to happen in the history of cellular communication, it has until recently been largely about communicating within borders. Last year saw progress here, with a surge in operators looking beyond domestic roll-out and starting to provide roaming capabilities.

LTE roaming is though a problematic hurdle for many in the operator community. As an all-IP proposition, LTE is something of a Year Zero for a world that still leans in part on legacy standards. Offering LTE roaming challenges operators to embrace a whole new set of commercial agreements and technical interconnections to take the place of SS7 signalling.

Critical to this phase of market development has been the work of carriers, supporting their MNO customers with IPX. As carrier investment flips from GRX to pure IPX, built independently of the public internet, so MNOs with the right carrier relationships have been able to peer all the more easily, both at data and signalling level. By such means have carriers been giving mobile operators access to the building blocks they need to offer LTE roaming, and many have been taking advantage.

LTE roaming appears, as was forecast, to be the killer application that IPX was waiting for, each now acting to fuel the other’s growth: “With many mobile networks transitioning to LTE, IPX has certainly gained traction in the last 12 months,” says Ravi Palepu, head of telco solutions for IT software and services provider Virtusa. “An IPX ecosystem with a common interconnection model and roaming bilateral agreements will underpin end-to-end mapping of IP classes of service. Mobile operators can provide a consistent customer experience, even on partner systems, to support the rising use of service level agreements and the introduction of tariffs, tiered by QoS levels on a global scale.”


Truly global roaming

One of the key movers in the carrier community has been Belgian carrier BICS, reporting earlier this year a huge increase in the number of its operator customers deploying LTE roaming in the wake of a 70% increase in its LTE roaming capabilities in 2014. Its IPX platform now enables over 150 operators to offer roaming across 75 countries, granting their customers access to all manner of high quality services while abroad. It followed up early LTE roaming launches in Asia, North America, Europe and Africa during 2013 by last year extending that capability into Russia, South Africa, the UAE, Saudi Arabia, France, Poland and Rwanda.

Mikaël Schachne, VP mobile data business with BICS, is happy with the rapid development of the LTE market and anticipates that 2015 will be another important growth year for roaming: “Around 50 operators joined the roaming community last year, which is very strong take up,” he points out. “It’s a consequence of the worldwide acceptance of LTE. Around 360 LTE networks are now live around the world. It’s become a mass market in just a year.” 

He says BICS has been able to capture about 25% of the LTE roaming market: “As operators join us they are launching end user services and that is fuelling traffic over our IPX,” he adds. “IPX transport is in huge growth right now, around 400% a year. And of course it’s pure LTE business, no 3G at all to cloud the figures. It’s my perception that users are really enjoying the benefits of LTE roaming.”

While Schachne sees LTE roaming being adopted all over the world, he says certain regions definitely have a first mover advantage – namely the US and Asia: “Europe is fighting back and bridging the gap right now, and there’s a lot going on in the Middle East,” he says. “It’s not only western Europe but eastern Europe too, Russia for example.”

He feels sure that history will judge 2014 to have been the take-off year for LTE roaming, but that 2015 is when the fruits of early investment will be enjoyed: “There’s now 50 countries where you can roam on LTE,” he claims. “Operators are joining our IPX cloud, but still need to make bilateral deals between themselves which takes time. We’re seeing a lot of peering announcements. This year will be about carrying on with the building of the environment, but also about working on the reach and on making services available for all destinations. We’ll be leveraging the environment we set up in 2014.”

BICS, he says, is now busy adding value added services so that operators can get the most out of the LTE business: “We can help them develop new solutions. We can now expect carriers to begin utilising the whole spectrum of services enabled by IPX, including deploying next generation voice services and value added packages for subscribers, to further enhance services for their own customers and incoming roamers."


Balancing data and voice

 There is however no escaping the fact that LTE roaming at the present point is mainly a data story and not a voice one, and that seamless voice roaming over LTE is a problematic challenge that operators have yet to embrace, fraught with possible wrong turnings and blind alleys.

“Mobile data roaming will see a significant growth in comparison to voice,” points out Virtusa’s Palepu. “In case of LTE voice roaming, we have to consider LTE coverage and adoption globally, taking account of both operators and consumers. In regions where mobile operators do not have coverage, they rely on old circuit-switch systems or voice over Wifi, which will impact LTE roaming traffic.”

The journey to VoLTE-based roaming is likely to be complex, and by no means a matter of flicking a switch for instant transformation. As LTE networks get built out and run concurrently with legacy networks, operators seeking to offer roaming may have to juggle the use of circuit switch fallback with VoLTE roaming, at least until all necessary interconnections are complete and the transition to full IP realised.


IPX may furnish the answer. Operators will be hoping to leverage IPX to deliver a pretty much flawless LTE service, and use it to establish the greatest possible number of LTE connections and multiple services – voice and data - within a single platform.

“LTE implementations present challenges that can only be addressed with the high-performance technology of IPX,” concludes Mun-Kein Chang, vice president of advanced signal and network interoperability, mobile transaction services with roaming solutions vendor Syniverse. “In order for LTE roaming to work, there must be an IPX in place.”

Last year’s LTE roaming growth via IPX was, he thinks, just the beginning of a growth inflexion curve: “With IPX as the key enabler for LTE roaming, offering secure connections with bandwidth capable of handling the surge of data from smart devices, data can flow through the network according to class-of-service prioritizations so that critical voice packets are routed with minimal delay, latency or jitter to provide end users with a seamless service.”

IPX, he says, also enables one-to-multiple connections and services all within the same network to allow operators to provide users with the widest range of coverage while reducing the number of connections an operator must manage while accessing solutions like messaging and intelligent roaming. He points out too that the seamless nature of VoLTE working in a LTE roaming session makes roaming voice is the next likely step before the year is out.

“IPX providers will be critical to offering international VoLTE roaming,” believes Chang. “No single LTE operator, no matter how big their footprint, has the ability to create relationships from the ground up with enough partners around the world to make VoLTE roaming work fully. But by turning to the IPX provider community, they have options.”

Some might try a hubbing model, where the operator has a single simple relationship with the IPX operator who then decides how to connect them to other operators as needed. But of course not all IPX providers have the same focus, some being natural specialists in roaming while others are more orientated towards voice and transmission.

Such is the radical, game changing nature of LTE that many operators will as yet be unclear exactly how they will be serving their customers over the next year or two. But partnership with the right carrier, and with a carrier that has themselves adopted an appropriate IPX strategy, would appear to be a prerequisite for success.



While VoLTE roaming is clearly a huge growth area for the future, it is not yet obvious which model will predominate as it evolves.

The GSMA has been backing a collaborative initiative involving several leading mobile operator names, between them exploring aspects of VoLTE roaming before actual commercial services get launched towards the back end of this year.

There is a heavy Asian flavour to the list of collaborators, as is perhaps customary with cutting edge 4G experimentation. Names include China Mobile, KT, NTT DOCOMO and SK Telecom, with KPN and Verizon also represented. Part of the initiative has involved assessing the relative merits the two possible models for VoLTE roaming – namely S8 HR (S8 Home Routed) and LBO VR, (Local Break Out Visited Network Routing).

Phase one of the trial is now complete, covering registration, deregistration, voice call and video call testing, and GSMA members have been pondering its results before deciding next steps.

As part of the trial, NTT DOCOMO, KT and Verizon Wireless proved for the first time, they say, that VoLTE roaming was feasible between different regions of the world. This trial used the S8HR architecture, based on the existing LTE data roaming platform, which the GSMA seems to believe is the most effective way to commercialise high-definition voice and video roaming services with full end-to-end carrier-grade voice and video quality. The trial calls were made over IPX to replicate a normal commercial environment.

China Mobile, KPN and iBasis meanwhile have also completed VoLTE roaming trials, but this time based on LBO VR architecture. IBasis said it was satisfied after the trial that it had the basis to allow operators to offer the full VoLTE experience when roaming abroad, and expects consumers to be able to enjoy a high quality of voice call while making downloads in the background. It says its network supports both local breakout and home routing.

A hybrid model where carriers support both competing VoLTE roaming models seems likely, says Christian Michaud, senior vice-president of product and business strategy in the global voice solutions business unit for Tata Communications: “I don’t see the market choosing one over the other,” he adds. “Support for both is more likely. We’ll see a mix of traffic. Carriers are engaged in a number of trials, with no clear winner at the moment.”

“We’ll support all the VoLTE roaming models being explored by the GSMA,” agrees Divya Ghai Wakankar, head of voice innovation with BICS. “There’s a lot of discussion here while specifications are being defined.”