How to prevent being added to groups without permission
Spammers and scammers like to use groups to add you to their own sick plans.
To prevent this, go to your Telegram settings.
Tap on Privacy and look for “Who can add me to groups and channels”
Change this to “Nobody” or “My contacts” if you wish.
There are other settings you can change too.
Remember that only your contacts can see you phone number, unless you have set it as “Visible”.