Administrative Regulations for Equal Access Services of Telecommunications Enterprises Article 17

If subscribers apply for using the long-distance or international Voice-based Telecommunications Universal Service offered by other telecommunication enterprises by means of call-by-call selection service, they shall put forward the applications in written form or in another appropriate way to the telecommunication enterprises of the long-distance or international network Voice-based Telecommunications Universal Service. Except for subscribers using mobile phone numbers.
中文原文 電信事業平等接取服務管理辦法第17條
用戶申請以撥號選接方式使用他電信事業所提供之長途或國際通信語音服務,應向提供長途或國際通信語音服務之電信事業提出。
但使用行動通信號碼之用戶不在此限。

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