My phone rang
Let's start with the fundamental legislative act - the Law "On Communications". Article 53 1 is devoted to databases of subscribers of communication operators. This refers to information that allows ukraine phone number library identifying the subscriber or his terminal equipment. It includes, in particular, the full name and mobile phone number, as well as the subscriber's address or the address of the terminal equipment installation, subscriber numbers and other data. This type of information also includes information about connections, traffic and subscriber payments.

According to paragraph 1 of Article 53, this information may be transferred to third parties only with the subscriber's consent. Operators also have the right to create publicly available databases for customer information and reference services. Therefore, there is nothing illegal in the fact that they will call you on your mobile phone number, call you by your first name and patronymic, and offer to listen to an advertising message. These actions are clearly spelled out in Article 53 of the Law "On Communications". It also stipulates that if you do not want the data to be placed in publicly available databases, you need to go to the nearest operator's office and write a corresponding statement.
With the right of transfer
Personal telephone calls are popular with many service companies that are not regulated by the Law on Communications. Since they use personal information about citizens, they must comply with Federal Law No. 152-FZ On Personal Data. According to this document, such an organization becomes a personal data operator and must register as such with Roskomnadzor. It has the right to use information received from another company, for example, purchased from a communications operator under an agreement. With one caveat: the purpose for which this data was originally collected must be preserved. In fact, this is how the very same client big data is formed (big data), which is actively experimented with by both commercial companies and government organizations.
If the telecom operator has sold the subscribers' contact information to another commercial company, and it also uses it for information and reference services, then everything that happens is within the law. Obviously, if a person has prohibited the operator from disclosing personal data to third parties, then this information should disappear from all those telephone call databases that are formed using the information purchased from the telecom operator. But there is a nuance here: the operator cannot guarantee that it has transferred the subscribers' personal data to a law-abiding commercial company, and not to scammers. Those who are called by product or service providers have to deal with this.
Is it up to the drowning man to save himself?
In October 2018, Megafon, Mail.ru and Yandex created the Association of Big Data Market Participants 2 on the principles of a self-regulatory organization (SRO). As a rule, such organizations are created in those business segments for which the problem of unscrupulous service providers has become relevant.