As VoLTE becomes real, carriers must address roaming urgently
By the MOSA (Mobile Operator Strategy Analysis) Team
As cellcos start to roll out VoLTE (Voice over LTE), or pencil in dates to do so, the early issues, such as handset availability, are giving way to fears about roaming, service quality and signal storms.
The basic standards are in place to support interoperable 4G voice services, notably the Diameter signalling protocol and the IPX exchange. However, these are relatively immature technologies in real world use, and may bring problems of their own, such as a huge growth in the volumes of Diameter signalling on networks.
One of the first priorities, if VoLTE is to be rolled out by most 4G cellcos and not just a handful, is to open up IPX access easily to all the operators. This is the goal of a new initiative led by the GSM Association and another industry body, the i3forum. They are to co-ordinate live commercial pilots for voice IPX, to be conducted by mobile and fixed operators including Deutsche Telekom, Orange, Telecom Italia, Telefonica and TeliaSonera. These pilots will be used to formulate the technical and commercial agreements needed to use IPX to interconnect voice services on a broad basis, and avoid the tangle of bilateral roaming deals which characterized – and slowed down – roaming in previous mobile generations.
“As we move to an all-IP world, customers will continue to demand high quality and high reliability for their voice services,” said Alex Sinclair, CTO of the GSMA. “By providing global interoperability, this initiative will help to drive the widespread deployment of services such as VoLTE, with the same quality of service that consumers have come to expect.”
IPX is the next generation, all-IP successor to GRX (GPRS Roaming Exchange, the key roaming framework for 2G and 3G data). IPX was designed to support consistent user experience even on partner systems, and so can support the rising use of service level agreements in mobile, and the introduction of tariffs tiered by QoS levels. It does this by guaranteeing enough bandwidth to keep services running at optimum speeds. It is increasingly being adopted as a standard for interconnecting fixed and mobile carriers, MVNOs and over-the-top providers, enabling international giants like BT to work with large numbers of partners and deliver common services across vast networks.
IPX in the mobile world lives within a GSMA-defined communications ecosystem which supports multiple services – voice, data and signalling – over a single IP connection and provides many other benefits, including enhanced voice quality, cascaded billing and payments and – because an IPX is physically and logically separate from the public internet – security. Within this, IPX enables the use of Diameter signalling for the exchange of policy, authentication and mobility information between networks as users roam.
An IPX approach could save operators the time and complexity of opening up their individual SIP interfaces to one another to enable VoLTE roaming, but will not, of course, remove the need to negotiate commercial deals or comply with changing regulations. However, the GSMA believes its new partnership will also help to draw up templates for commercial contracts to reduce time to market.
Carriers are starting to launch IPX services under their own steam too however. Last week saw Ooredoo (Qatar Telecom) tapping into Tata Communications’ IPX+ connectivity platform, to launch voice over IPX services. Ooredoo plans to consolidate its entire network around an IP-based backbone, supporting a suite of services such as signalling, data roaming (GRX and IPX) and VoLTE roaming. Tata says 140 operators in 40 countries have adopted its IPX+ services.
Meanwhile, TeliaSonera’s international carrier unit has launched an IPX platform based on its global fiber backbone, one of the largest such networks in the world at this point. It will be available to Telia group members and external operators and initially supports roaming and signalling plus VoIPX, with LTE signalling to be added later this year.
TeliaSonera says its IPX architecture exceeds GSMA and i3forum requirements, and Veysel Aral, president of the carrier’s Eurasia division, said: “Once people experience higher quality, they won’t be willing to go back. IPX is crucial to meeting the growing demands of mobile customers.”
Despite all these challenges, the two big US carriers both plan to launch VoLTE late this year or early in 2014. AT&T says it will move this year, while Verizon says it will be network-ready for VoLTE and the related RCS (Rich Communications Services) technology this year too, but launch dates will be decided by the marketing teams. CTO Tony Melone told a recent conference that the operator “won’t launch before it’s ready”, citing the same concerns as many other cellcos, about whether the new platform can deliver the same quality that users expect on 2G/3G, especially with regards to consistency of QoS and roaming. He said:
“When we do it, we want to make sure it reaches the same high quality standards of our current voice network.”
