How to Obtain a Telegram-Linked Mobile Number
In this article, I mainly talk about Telegram, although the issue also concerns a number of other messengers where a username is used, and the mobile phone, although linked to the account, remains hidden from users outside the contact list. This creates a false sense of anonymity, as the number is securely hidden, and nothing can be figured out from the username. But in reality, this is not the case.
Imagine yourself as the owner of a messenger: you created a messenger and to effectively promote it, you implement the ability to check which of the user's contacts has already installed your app, in order to immediately connect interlocutors, as well as notify users if someone from the contact list registers in your messenger.
Law enforcement agencies and hackers take advantage of this and create devices where all phone numbers will be added to the contacts. Your messenger processes this data and reports which username belongs to which number.
But you, as the owner of the messenger, understand that this will negatively affect your reputation, and you make a perfectly logical decision – you limit the number of contacts to one account. Let this be the number 10,000. It is unlikely that even the most sociable person will have more than ten thousand numbers in their phone book, even if they have several phones.
Now, to create a tool to verify the number linked to the account, for example in Russia, it is necessary to break millions of phone numbers into groups of ten thousand and write software to simulate mobile devices. Difficult? It is definitely not easy, but nothing is impossible.
You must understand: this threat cannot be defended against. You can complicate the task with restrictions, but for special services or serious companies, it will not become unsolvable. However, hackers and private researchers will not be able to implement this due to a lack of resources, although there may be other ways to obtain data that I am not aware of.
After all, in addition to software solutions, an active phone number database is needed; otherwise, iterating through all possible values will lead to billions of combinations.
What should you take away from this chapter? Only one thing: it is not difficult to find out the phone number linked to Telegram or an account in a similar messenger if we are talking about law enforcement agencies or special services. To obtain the number, it is enough to know your username.
It is recommended online to restrict Telegram's access to contacts to protect against the threat of obtaining the number. I hope you understand that this will not help in any way, as Telegram knows your number regardless of access to contacts. The only protection remains the use of virtual numbers – a method that cybercriminals and various types of fraudsters have long used when creating accounts in Telegram. There are many such services available.