From 2013, foreign investment by incorporated companies in facility-based telecommunications businesses is permitted up to 100% foreign ownership for countries with which Korea maintains a Free Trade Agreement (EU, EFTA, Chile and USA), with the exception of KT, SK Telecom and LG Plus - the three major players in the Korean market. A 49% equity limit continues to apply to investments made by Korean incorporated enterprises with 15% or more foreign investment from a country with which Korea does not have a Free Trade Agreement. Companies established in Korea but with more than 15% of foreign ownership will also have to go through a public-interest test prior to conducting investments in the telecommunications businesses.
"Article 8 (Limitations on Stock Holdings by Foreign Governments or Foreigners)
(1) A foreign government or foreigner may hold stocks (excluding different classes of shares with no voting rights prescribed in Article 344-3 (1) of the Commercial Act, but including voting stock equivalents, such as security depositary receipts, and equity shares ; hereinafter the same shall apply) of a facilities-based telecommunications business operator who meets the criteria prescribed by Presidential Decree for the type, installation area, etc. of telecommunications line equipment (referring to a person who has filed for registration under Article 6 (1) or has filed a report under the proviso to Article 6 (1); hereinafter the same shall apply) within 49/100 of the total number of outstanding stocks of the facilities-based telecommunications business operator, when aggregating all of such stocks held by foreign governments or foreigners.
(2) Where a foreign government or foreigner (including a related person defined in subparagraph 6 (a) of Article 2 of the Act on Corporate Governance of Financial Companies; hereinafter the same shall apply) is the largest shareholder (referring to the largest shareholder) defined in subparagraph 6 (a) of Article 2 of the Act on Corporate Governance of Financial Companies; and in such cases, "financial company" shall be construed as "corporation"; hereinafter the same shall apply) who holds at least 15/100 of the total number of outstanding stocks of a corporation, such corporation (hereinafter referred to as "deemed-foreign corporation") shall be deemed a foreigner. 
(3) Neither of the following corporations shall be deemed a foreigner, even if it satisfies the requirements prescribed in paragraph (2): Provided, That the same shall not apply to foreigners referred to in Articles 10 (1) 3 and 86 (3) ):  
1. Where a corporation holds less than 1/100 of the total number of outstanding stocks of a facilities-based telecommunications business operator under paragraph (1);
2. Where the largest shareholder of a corporation is the foreign government or a foreigner of the other party to a free trade agreement determined and publicly notified by the Minister of Science and ICT, from among bilateral or multilateral free trade agreements which the Republic of Korea has entered into with foreign countries and have been ratified, and holds at least 15/100 of the total number of its outstanding stocks; and where such corporation is found by the Minister of Science and ICT unlikely to harm public interests through an examination of public benefits referred to in Article 10.
[...]
Article 10 (Examinations of Public Benefits of Possession of Stocks by Facilities-Based Telecommunications Business Operators) 
(1) A Public Benefit Examination Committee (hereinafter referred to as the "Committee") shall be established under the jurisdiction of the Ministry of Science and ICT in order to examine whether any of the following cases impairs public interests prescribed by Presidential Decree (hereinafter referred to as "examination of public benefits"), such as national security, public safety, and maintenance of order: 
1. Where a person holds at least 15/100 of the total number of outstanding stocks of a facilities-based telecommunications business operator, including those stocks held by a related person defined in subparagraph 6 (a) of Article 2 of the Act on Corporate Governance of Financial Companies (hereinafter referred to as "related person");
2. Where the largest stockholder of a facilities-based telecommunications business operator changes;
3. Where a facilities-based telecommunications business operator or any stockholder of a facilities-based telecommunications business operator concludes an agreement with a foreign government or a foreigner on important managerial matters prescribed by Presidential Decree, such as the appointment and dismissal of executive officers and the transfer or acquisition of business;
4. Where any person who has de facto management rights for a facilities-based telecommunications business operator changes, as prescribed by Presidential Decree.[...]
(5) Where the Minister of Science and ICT deems, as a result of an examination of public benefits prescribed in paragraph (1), that cases falling under any subparagraph of paragraph (1) are likely to impair public interests, he or she may issue an order to modify the details of an agreement, to suspend the implementation of such agreement, to suspend the exercise of voting rights, or to sell relevant stocks. 
(6) The scope of facilities-based telecommunications business operators who shall report or may request an examination of public benefits pursuant tot to paragraph (2) or (3) shall be as follows:   
1. A facilities-based telecommunications business operator who operates and manages important communications referred to in Article 92 (2) 3;
2. A facilities-based telecommunications business operator possessing a satellite for which a space station is established under Article 20-2 (3) of the Radio Waves Act and subparagraph 30 of Article 29 of the Enforcement Decree of the same Act;
3. A facilities-based telecommunications business operator designated and publicly notified by the Minister of Science and ICT as a facilities-based telecommunications business operator prescribed in Articles 35 (2) 1 and 3, 39 (3), 41 (3), and 42 (3);
4. A facilities-based telecommunications business operator referred to in Article 8 (1) who provides telecommunications services using the frequency allocated according to the Radio Waves Act: Provided, That excluded herefrom shall be a facilities-based telecommunications business operator whose telecommunications service turnover of the preceding year is less than an amount determined by Presidential Decree in consideration of the market situation, market share, etc.;
5. A facilities-based telecommunications business operator referred to in Article 8 (1) whose telecommunications service turnover exceeds an amount publicly notified by the Minister of Science and ICT in consideration of the market situation, market share, etc., from among facilities- based telecommunications business operators whose telecommunications service turnover of the preceding year exceeds 30 billion won. [...]"(Telecommunications Business Act (No. 3686 of 1983), last amended by Act No. 18451 of 2021, Articles 8 and 10 [unofficial translation])
-------------------
""Article 4 (Liberalization, etc. of Foreign Investment)   
(1) Except as otherwise prescribed by the Acts of the Republic of Korea, a foreigner may engage in, without restraint, various activities of foreign investment in the Republic of Korea.
(2) No foreigner shall be restricted from making any foreign investment prescribed in this Act, except in the following circumstances:
1. Where he or she threatens national security and public order;
2. Where he or she has harmful effects on public health and sanitation or environmental preservation or is against Korean morals and customs;
3. Where he or she violates any Act or statutes of the Republic of Korea.
(3) The categories of businesses in which foreign investment is restricted in accordance with any of the subparagraphs of paragraph (2) and the details of restrictions shall be prescribed by Presidential Decree. [...]" (Foreign Investment Promotion Act (No. 5559 of 1998), last amended by Act No. 17799 of 2020, Article 4 [unofficial translation])
-------------------
"Article 5 (Types of Business Restricted by Foreign Investment) 
(1) In accordance with Article 5 (1) 1 of the Decree, the types of businesses subject to restrictions on foreign investment announced by the Minister of Trade, Industry and Energy in consultation with the competent minister are as shown in Attached Table 2.
(2) When a foreign investor invests in a business that has permissible standards among the industries listed in Attached Table 2, foreign investment may be made within the permissible standard.
[...]
[Appendix 2] Categories of Business with Restrictive Foreign Investment and Criteria for Permission (pursuant to Article 5)
Classification | Type of Business | Criteria for Permission [...]
61210 | Wire communication business | Permitted if the total stocks (limited to the stock with voting rights and including depositary receipts and other things equivalent to stocks with voting rights) held by foreign governments or foreigners (including foreign fictitious corporations) dose not exceed 49/100 of total issued stocks (Provided, That although no foreigner, etc. shall be allowed to become the largest stockholder of KT, permission shall be granted if he/she holds less than 5/100 of total stocks). Foreign fictitious corporation: A corporation whose largest stockholder is a foreign government or foreigner (including special persons concerned under Article 9 (1) 1 of the Financial Investment Services and Capital Markets Act) who holds more than 15/100 of the total issued stocks thereof. Provided That, there shall not be deemed as a foreigner a corporation considered unlikely to impair public interests by the Minister of Science and ICT as a result of an examination on public benefits under Article 10 of the Telecommunications Business Act, which is a fictitious corporation of a national of other partner state of any free trade Agreement [...]." (Regulations on Foreign Investment (Ministry of Commerce, Industry and Energy Notice No. 1999-58 of 1999), last amended by Notice No. 2021-106 of 2021, Article 5 and attached Table 2 [google translation / unofficial translation of Table 2, source: Kotra])"
Telecommunications Business Act (No. 3686 of 1983), last amended by Act No. 18451 of 2021, Articles 8 and 10
Foreign Investment Promotion Act (No. 5559 of 1998), last amended by Act No. 17799 of 2020, Article 4
Regulations on Foreign Investment (Ministry of Commerce, Industry and Energy Notice No. 1999-58 of 1999), last amended by Notice No. 2021-106 of 2021, Article 5 and attached Table 2
[<a href="https://www.law.go.kr/LSW/lsInfoP.do?efYd=20190625&lsiSeq=206000&ancYd=20181224&nwJoYnInfo=N&ancNo=16019&chrClsCd=010202&efGubun=Y#0000">Act</a>],[<a href="https://www.law.go.kr/LSW/eng/engLsSc.do?menuId=2&query=TELECOMMUNICATIONS%20BUSINESS%20ACT">Act_Eng</a>],[<a href="https://www.law.go.kr/LSW/lsInfoP.do?nwJoYnInfo=Y&ancNo=16131&chrClsCd=010202&efYd=20190401&lsiSeq=206503&efGubun=Y&ancYd=20181231#0000">Act</a>],[<a href="https://elaw.klri.re.kr/eng_service/lawView.do?hseq=44627&lang=ENG">Act_Eng</a>],[<a href="https://www.law.go.kr/LSW/admRulLsInfoP.do?chrClsCd=&admRulSeq=2100000136409#AJAX">Reg</a>],[<a href="http://openknowledge.kotra.or.kr/handle/2014.oak/23472">Other</a>]