Is it possible to find out the user's contacts through the Telegram bot or offer to send a message or a link to his contacts?

Question

Bots

actually the question is in the title. at least hint, if you know which direction to move in this matter, thanks in advance

Answer 1

Get into the user's contacts - no.
Write a message to the user "send a message / link to your contacts" - this is possible.

Answer 2

The telegram had (or maybe still has) an ideological vulnerability, which is being exploited to the fullest and customer databases are roaming the Internet.
When you install telegrams on your phone, a request with a list of contacts is sent to the server, and a response is returned back, which of the contacts are already in the telegram (if one of your contacts has installed telegrams, a message also arrives).
Accordingly, the method of collecting data, we take 100500 sim cards in our hands, and begin to sort through the entire range of phone numbers. I suppose telegram puts spokes in the wheels here, preventing too many and often requests from being made, respectively, the number of sim cards will directly determine how long the search will take.
The only thing that was done in the telegram was that they provided the user in the settings with the opportunity not to give out their contacts to the server (or, most likely, the server should not tell others that you are in the contacts of other people), by default it is disabled.