South Korean operator LG Uplus completed tests of core technologies supporting high-quality voice running on a standalone (SA) 5G network, preparing the way for the rollout of the next-generation service later in the year.

In a statement, the third largest operator in the country by subscribers, said the tests verified the performance of evolved packet system (EPS) fallback and voice over 5G (Vo5G), and demonstrated it is ready to deliver stable and high-quality 5G voice services.

Park Song-cheol, executive director of LG Uplus’ Network Technology Operation Group, said it was successful in securing the core 5G-based voice call technologies for the commercialisation of SA 5G.

The operator said the current 5G networks launched in April 2019 are based on the non-standalone (NSA) architecture, which also rely on 4G core networks, with voice calls running on LTE infrastructure. It noted that since 5G and LTE cannot be used simultaneously in SA mode, it plans to use EPS fallback or Vo5G.

EPS fallback can provide stable voice service using LTE networks, but may have quality problems including longer call connection times compared with Vo5G, which LG UPlus said enables faster connections on a stable 5G network, but can face performance issues on LTE infrastructure.

The company commercialised VoLTE in 2012.

LG Uplus, and rivals SK Telecom and KT, are expected to switch on SA 5G networks before the end of the year.