BARCELONA -- Mobile World Congress 2015 -- Wholesale carrier BICS is set to announce details of a forthcoming trial of international VoLTE services involving ten operators, Light Reading has learned.

The trial should help speed up the rollout of international VoLTE services for customers already able to make use of the technology. The news comes days after Japan's NTT DoCoMo Inc. (NYSE: DCM) claimed to have made the first transoceanic VoLTE call during tests with Verizon Wireless in the US and Korea's KT Corp. (See Verizon Takes Radio Dot to Detroit, VoLTE Overseas .)

Speaking to Light Reading here, Jorn Vercamert, vice president of BICS 's voice business, said the operator would announce full details of the international VoLTE trial in the "next few weeks" as it works on the development of a VoLTE transit and roaming service.

Only about 20 operators internationally have so far launched VoLTE services, according to Vercamert. But he expects that number to grow to about 100 by next year, opening up a major opportunity for the Belgian player.

Even so, the rollout of international VoLTE services faces some big technical and commercial challenges.

One issue is whether local breakout or home routing is the best option for VoLTE roaming. As noted in a recent paper from Alcatel-Lucent (NYSE: ALU), traffic is serviced by the home network in the case of home routing but by the network a subscriber is visiting with local breakout.

The GSM Association (GSMA) favors local breakout because it is more efficient, according to Alcatel-Lucent, but this technique requires the home network owner to relinquish control of its customer. Local breakout could, therefore, meet with resistance if the home network owner does not have a strong relationship with the owner of the visited network.

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Another concern is pricing: While Vercamert insists that VoLTE will use only a fraction of the bandwidth needed for other data services, many customers switch off data functionality when they are travelling to avoid being hit by high data charges. That increases the need for integrated solutions running over the core network, according to Alcatel-Lucent.

"We have to listen to what operators want -- it's not our role to say what the right roaming model should be," says Vercamert. "Operators will go for one scenario or another depending on their particular circumstances and we need to be accommodating and flexible."

The migration to data technology is putting a lot of pressure on classical wholesale operators, acknowledges Vercamert, and forcing BICS to invest in various new services and capabilities.

"More and more we need to be an enabler of innovation and we've been launching services aimed at helping customers to optimize their operations," he says.

BICS has already developed products in areas such as hosted RCS and fraud analytics and has also been investing in new facilities. Last year it expanded its presence in China and opened an office in San Francisco and it is now planning further investments in Africa, says Vercamert.

BICS saw revenues fall on a year-on-year basis by 5.4% in 2014 due to the decline at its voice business. But it expects overall sales to remain stable this year.

— Iain Morris, , News Editor, Light Reading