Telecommunications Universal Service Regulations Article 5

Voice-based Telecommunication Universal Service includes uneconomic public payphones and telephone service in uneconomic areas.
中文原文 電信普及服務管理辦法第5條
語音通信普及服務包括不經濟公用電話服務及不經濟地區電話服務。

English translation for reference only; the Chinese text prevails. Not legal advice.