Abstract: The subject of the study is to identify effective methods of legislative work to counteract the use by telephone fraudsters of such technical means as illegal substitution of SIM cards and Internet services for substitution of incoming call numbers. The general scientific methodology of dialectical (meaningful) logic and comparative analysis of practical problems and legislative activity of federal authorities are used. Fraud causes huge damage to society and incurs huge costs to the state. The global spread of the Internet has allowed scammers to export their activities to a fast-growing market and attract previously untapped consumers. The evolution of technologies and the spread of fraudulent approaches on the Internet have exacerbated the problems faced by victims. The results serve as evidence that when detecting and timely stopping attempts at telephone fraud (suspending suspicious transactions), legislative support and the formation of a subordinate regulatory framework are necessary for the interaction of financial organizations, telecommunications operators and law enforcement agencies. The development of smartphones and cellular networks increases the need for mobile advertising and targeted marketing. However, it also causes invisible security threats. We have found that phone fraud with fake phone numbers with a very short service life is becoming more and more popular and is being used to deceive users. The article is devoted to the consideration of the problem of legal regulation to ensure information security. As phone fraud becomes more common, it is extremely important to understand how to increase the effectiveness of prevention. Conclusions are drawn about the need to strengthen the centralization of countering intruders in order to increase the effectiveness of preventing telephone fraud, following the example of creating an interbank digital platform "Know your Customer".