On 1 October 2020, the Act amending the Telecommunication Act against undesired control in the telecom sector and a related implementing decree entered into force. The new rules introduce a mandatory notification requirement for any investor – regardless of nationality – who seeks to obtain a “predominant control” in a “telecommunication party” leading to a “relevant influence” in the telecom sector. The government may prohibit or unwind a transaction that meets these criteria if it would jeopardize national security or public order.
"Chapter 14a. Unwanted control over telecommunications parties [...]
Article 14a.2
1 A person who intends to acquire predominant control in a telecommunications party shall notify Our Minister of this intention if this control leads to relevant influence in the telecommunications sector as referred to in Article 14a.4, subsection 3 . A notification does not have to be made by a legal entity independent of a listed telecommunications party whose object is to represent the interests of the telecommunications party and an affiliated company and which, after the announcement of a public offer for a maximum period of two years to protect the telecommunications party. [...]
3 Our Minister will decide within eight weeks of receipt of the notification whether a ban will be imposed on the basis of Article 14a.4, first paragraph . If further investigation is necessary, Our Minister may extend the term by six months. [...] 
5 If, after a notification as referred to in the first paragraph, it appears that there is a foreign direct investment that falls within the scope of Regulation (EU) 2019/452 of the European Parliament and of the Council of 19 March 2019 establishing a framework for the screening of foreign direct investments in the Union (OJEU 2019, L 79), the term referred to in the third paragraph, second sentence, can be extended by a maximum of three months.
[...]
Article 14a.3
Predominant control exists if the holder or acquirer of that control after the acquisition:
a.alone or together with persons acting in mutual consultation, directly or indirectly has at least 30 percent of the votes in the general meeting of a legal person;
b.may appoint or dismiss more than half of the directors or supervisory directors of a legal entity, whether or not by agreement with others, alone or together with persons with whom they act in concert, even if all persons entitled to vote vote;
c.has one or more shares with a special statutory right to control;
d.has a branch office, being a telecommunications party;
e.as a partner becomes fully liable to creditors for the debts of the company acting under its own name, or
f.owns a sole proprietorship.
Article 14a.4
1 If, in the opinion of Our Minister, existing or forthcoming predominant control in a telecommunications party by a certain party may lead to a threat to the public interest, Our Minister shall prohibit him or her subject to conditions precedent from retaining or acquiring predominant control. in this telecommunications party. If Our Minister intends to impose a ban, he will ask the telecommunications party for an opinion on the intended decision. He sets a time limit for submitting his opinion.
2 There can only be a threat to the public interest if the predominant control leads to relevant influence in the telecommunications sector as referred to in the third paragraph, and:
a.the transferee or holder is an undesirable person or is a state, entity or person known or reasonably suspected of intent to influence a telecommunications party to facilitate misuse or intentional outages,
b.the acquirer or holder has close ties with or is under the influence of a state, entity or person as referred to under a, or is a person in respect of whom there are grounds to suspect such ties or influence,
c.the acquirer or holder has such a track record that the risk that the consequences referred to in the third paragraph under a to d will occur is considerably increased,
d.the identity of the actual holder or transferee cannot be established, or
e.the acquirer or holder does not cooperate or does not cooperate sufficiently with the investigation into the circumstances under a to d.
3 There is relevant influence in the telecommunications sector if misuse or intentional failure of the telecommunications party, referred to in the first paragraph, and any other telecommunications parties in which the holder or acquirer or the group of which the holder or acquirer is a part retains or acquires predominant control until:
a.an unlawful breach of the confidentiality of the communication, or an interruption of the internet access service or telephone service of more than a number of end users to be determined by order in council;
b.an interruption of the availability or verification of services and applications specified by order in council that are provided via the internet insofar as those services exceed a threshold to be determined by that order in council;
c.an interruption in the availability, reliability or confidentiality of a product or service designated by order in council for the purpose of a public task in the field of national security, defence, the maintenance of the legal order or assistance;
d.an unlawful infringement or interruption as referred to in parts a or b with regard to a combination of services and applications as referred to in those parts that together exceed a threshold value set by that order in council;
e.other serious consequences referred to by order in council with regard to the continuity of services by a telecommunications party or the confidentiality of communications. [...]" (Telecommunications Act of October 19, 1998; as amended by the Act of 20 May 2020; Articles 14a.2, 14a.3 and 14a.4 [google translation])
Telecommunications Act of October 19, 1998; as amended by the Act of 20 May 2020; Articles 14a.2, 14a.3 and 14a.4
[<a href="https://wetten.overheid.nl/BWBR0009950/2021-07-01">Act</a>]