HKT, Huawei complete HSS/VoLTE network migration in Hong Kong

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HKT and Huawei have successfully completed the Home Subscriber Server (HSS) / Voice over LTE (VoLTE) cutover, paving the way for the full integration of the HKT and CSL mobile core networks.

The HSS/VoLTE cutover was the first step of a series of migrations for integrating the two mobile core networks of HKT and CSL into a newly built integrated core network, a strategic move that followed HKT’s acquisition of CSL to unify user experience with a homogenous and simplified service set. In the long term, it enables HKT to offer advanced services, even more extensive roaming coverage, as well as one of the world’s best mobile broadband networks with the highest data speed. The entire network integration is expected to be completed in 2016.


This first migration was the most critical and difficult in the entire integration as a live, dynamic database for several million CSL subscribers had to be transferred from the HSS, which was considered as the brain of a mobile network, of the original vendor to that of HKT’s existing partner Huawei. The VoLTE network migration encompassed IP Multimedia Subsystem (IMS) and circuit switched domains, including the core 2G/3G/4G/IMS HSS.

A dedicated team from HKT and experts from Huawei spent around nine months building the new integrated core network and planning for this cutover, including initial design, equipment installation and commissioning, systems integration and testing, as well as user acceptance testing. The team also performed five rehearsals of which three were performed on live systems. Supported by close to 500 Engineering and IT specialists from HKT and Huawei, the migration was finally completed in 48 hours on December 12 and 13, 2015.

The migration was a huge success given its unprecedented scope, technical complexity and extensive coordination between two vendors. Without any precedence to take reference from, this migration was believed to be the world’s first live migration of 2G/3G/4G/IMS HSS plus IMS/VoLTE cutover from one vendor to another. This remarkable achievement was only made possible by cross-department efforts and Huawei’s support, demonstrating the spirit of “One Network One Team”.

Mr. Peter Lam, Managing Director of HKT’s Engineering, said, “The migration is a significant milestone in our efforts to present the most state-of-the-art mobile platform for network evolution and service excellence. Everyone has worked diligently as an indispensable part of one team towards building the one core network.”

Mr. Wang Yongde, Vice President of Huawei’s Core Network Product Line, said, “The network migration project required the convergence of packet switched, circuit switched and, most notably, IMS domains. The huge amount of data involved and the tight timeframe made network migration extremely challenging. Huawei is proud to have participated in the seamless migration of 2G/3G/4G networks to the new core network for HKT, fully demonstrating our strengths, especially in the VoLTE field.”

In partnership with Huawei, HKT has led the evolution of the mobile market in Hong Kong for several years. In May 2014, HKT was the first operator in Hong Kong to offer its 4G customers a VoLTE service while Huawei was the first solution provider to support a commercially available VoLTE service based on the latest 3GPP R10 standard in the world. In April 2015, HKT and Huawei demonstrated the world’s first LTE-A network by aggregating three 20 MHz carriers to breaking the world record for 4G network speeds with a peak throughout of 450 Mbps. In November 2015, HKT and Huawei further demonstrated the world’s first 4.5G 1Gbps mobile network at the Global Mobile Broadband Forum 2015 in Hong Kong. In June 2015, Huawei and HKT won the coveted “Best VoLTE Innovation” award from consultancy firm Informa at the LTE World Summit 2015.