According to this article from CoinTelegraph, Telegram denies making any agreement like this. Sees like it’s MTS trying to boost its advertising services (and charge clients more) with false promises:
Telegram spokesperson Remi Vaughn told Cointelegraph that the company hasn’t entered into any ad-related agreements with any Russia-based companies, including MTS:
“They may be accessing Telegram ad platform features via one of the global ad agencies we work with, but we can confirm that no partnership or agreement exists between Telegram and MTS.”
ideally telegram should confirm it's not selling phone numbers to anyone. but this is a relief.