Services like Telegram require a phone number for verification but giving out your personal phone number is a very risky proposition and a violation of your privacy. All it takes is one wrong move and your number is out in the public eye. It doesn’t take long from there to link a phone number to an identity and then to a face.
To avoid all of this I highly recommend none of you use Telegram with your real phone number. There are a million different ways to gain access to another phone number for long enough to validate your Telegram account. Once validated you will never need access to this number again.
Below are some links to places where you could get a throw away phone number for Telegram and other services…
Burner App: https://www.burnerapp.com
Google Voice: https://voice.google.com/
Free SMS: https://quackr.io/
Free SMS: https://smsreceivefree.com/
SMS for Bitcoin: https://smsprivacy.org/