[codedokode]

I assume there are some limits on number of uploaded contacts (probably on order of thousands) but they can be bypassed by creating thousands of accounts each with different contact list. One SIM card here in Russia costs as low as several dollars, and probably cheaper if bought wholesale, so it is not very expensive.

Also, here is a quote from an article in Russian [1], where it is claimed that there is a software to de-anonymize Telegram users:

> A phone number used by [Telegram] account @silovikicat was discovered using a program titled "Insider-Telegram" developed by the "Center of research of legitimacy and political protest". The head of the "Center" Eugene Venediktov explains: "Currently the database contains over 10 million of numbers. We just go through all possible numbers and check whether they are registered in Telegram: for example, we take all numbers starting with a prefix +7911 and check them. You automatically see all contacts from you address book in your Telegram, don't you? We just have a very "fat" address book with phones of all users from our country."

> When a phone number provided by Eugene is added into an address book, Telegram automatically matches it with account @silovikicat («Siloviks' cat»).

[1] https://meduza.io/feature/2019/08/10/kto-takoy-tovarisch-may...