Viber may be blocked in South Korea, after losing a patent suit filed by domestic operator SK Telecom in November, The Korea Herald reported, although there has been no official announcement of a ban.

SK Telecom claimed that Viber’s “feature of reorganising information from contact numbers saved in a smartphone into the application” violated a patent it had registered back in 2006. The operator sued Viber for four patent violations in November, but the court dismissed three of them.

According to TechCrunch, the patent is “incredibly vague” and could apply to other messaging apps, such as KakaoTalk, which is free and extremely popular in the country.