China Mobile, KPN and iBasis said yesterday they have completed the first international VoLTE roaming call between mobile operators based on IMS local breakout architecture.

iBasis said in a statement that the trial shows the potential for customers to have the full VoLTE experience while roaming overseas. VoLTE represents a significant gain in network efficiency and end-user convenience, with customers able to enjoy HD voice and make calls over the LTE network while making downloads in the background.

iBasis said its network now supports both local breakout and home routing and helps operators overcome challenges such as signaling and media interworking between VoLTE and non-VoLTE networks. The company said its VoLTE test environment with interconnection and test locations around the world helps operators prepare for commercial launch.

China Mobile has plans to commercially launch VoLTE service in China at the end of the year. China Mobile International and iBasis will provide the IPX inter-connectivity between China Mobile and KPN. Huawei is supplying the key network components.

At the beginning of the year 40 operators were in different stages of deployed VoLTE. The rapid roll out of 4G networks and uptake of 4G services globally will speed up the move to VoLTE services, which includes support for HD voice.

Global LTE connections passed the 250 million mark in Q1, according to Ovum. LTE connections in Asia Pacific increased 102 per cent from a year ago, hitting 100 million connections at the end of June.

In the past two quarters, China has added more than 22 million 4G connections, with China Mobile alone having 18 million LTE subscribers. The company expects to have 25 million connections by the end of the year, GSMA Intelligence predicts.

Ovum forecasts global LTE connections to exceed two billion by 2019 and account for a quarter of mobile broadband connections.