To ensure effective competition in the telecommunications service market, the competent authority is entitled to adopt control measures for those with market significance in the specific telecommunications service market if necessary.
When delimiting the scope of the specific telecommunications service market as described in the preceding paragraph, the competent authority shall take the following factors into consideration:
1. The technology and service development level;
2. The importance thereof in the overall telecommunications service market;
3. The region or range of competition and the demand or supply substitutability of that service;
4. The structure and competition of the telecommunications service market.
With respect to the determined scope of a specific telecommunications service market, the competent authority shall carry out a review every 3 years and hold a public hearing therefor to listen to the opinions of telecommunications enterprises and stakeholders.

Where the telecommunications enterprise of a specific telecommunications service market encounters any of the following situations, the competent authority may recognize it as an enterprise with significance in the market:
1. Can obviously affect the market price or service conditions;
2. The number of subscribers or revenue of telecommunications service items operated thereby is above the percentage announced by the competent authority;
3. Possess or control essential facilities.
Where the telecommunications service provider encounters any of the situations described in the preceding paragraph and fails to register itself as a telecommunications enterprise, it shall be deemed as a telecommunications enterprise under this Chapter and subject to the obligation thereunder accordingly.
Where the telecommunications enterprises are not in competition with each other and their external relationship is as described in Paragraph 1, all of them will be deemed as having significance in the market.
When determining enterprises with significance in the market, the competent authority shall not only follow Paragraph 1 and the preceding paragraph but also take the consolidation of the telecommunications enterprise and affiliated companies thereof into consideration.
Those enterprises determined as having significance in the market by the competent authority may submit supporting documents related to its operations in the specific telecommunication service market to the competent authority as an application for canceling the determination as prescribed in Paragraph 1.
Rules governing the market significance determination standards, procedures and cancellation; date of promulgation; and other related matters shall be promulgated by the competent authority.
The essential facilities as described in Subparagraph 3 of Paragraph 1 refer to those which are in compliance with the following conditions and are announced by the competent authority:
1. The facilities cannot be established separately or be replaced; otherwise, the establishment or replacement thereof would require a rather long period of time and high costs, showing no economic benefit.
2. Where the enterprise’ refusal of providing the facilities to other telecommunications enterprise will directly or indirectly obstruct other telecommunications enterprises from entering the market competition.