SK Telecom has become the first operator to surpass one million subscribers for the joyn Rich Communication Services (RCS) offering.

The South Korean number one operator reached the milestone on 15 February, just 50 days after the service – dubbed joyn.T – was launched.

joyn is a GSMA-backed effort by the operator community to compete more effectively with over-the-top players. It enables services such as enhanced messaging and voice, video calling and content sharing directly from the phone’s contact book, regardless of the network or device used.

SK claimed it has upgraded the performance of joyn since its launch, through system optimisation, server expansion and customer feedback.

It has also offered unlimited free-for-life joyn SMS and IMS services to smartphone subscribers via flat-rate plans, while data fees incurred from sending and receiving messages will not be deducted from data allowances.

SK plans to make joyn into a “total communication service” by linking it to its VoLTE HD Voice service and driving the development of other services by opening the suite’s API to outside developers.

“SK Telecom aims to integrate all means of mobile communication into joyn to make it the most attractive choice for customers seeking an accurate and enriched communication service,” said SK Telecom executive VP and head of product planning, Wi Eui-Seok.

The GSMA said SK’s success with joyn is likely to drive other operators and mobile device markets to accelerate the commercialisation of joyn services.

In November, Spain became the first country to offer a fully interoperable RCS service with the country’s three largest mobile operators – Telefonica’s Movistar and the local arms of Orange and Vodafone – launching joyn nationwide.