Administrative Regulations on the Establishment and Operation of the Dedicated Taxi Radio Station Article 15

Only one Car Station can be installed on each taxi.If more than one Car Station is found in a taxi, the responsible competent authority of highways shall notify the NCC to revoke the license of the additional Car Station and the Car Station equipment shall be managed in accordance with Administrative Regulations on the Controlled Telecommunications Radio-Frequency Devices.
中文原文 計程車專用無線電臺設置使用管理辦法第15條
一部計程車以架設一車臺為限。
經公路主管機關或有關機關查獲計程車重複設置車臺者,由該管公路主管機關通知本會廢止該重複設置之車臺執照,其車臺設備依電信管制射頻器材管理辦法規定辦理。

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