Q: Who can see my phone number?

On Telegram, you can send messages in private chats and groups without making your phone number visible. By default, your number is only visible to people who you've added to your address book as contacts. You can further modify this in Settings > Privacy and Security > Phone Number.

Note that people will always see your number if they know it already and saved it in their address book.

Q: How do I change my phone number?

You can change your number in Telegram and keep everything, including all your contacts, messages, and media from the Telegram cloud, as well as all your Secret Chats on all devices.

Important: Your mutual contacts (people in your contacts who also have your number) will get your new number added to your contact in their address book unless you have blocked them in Telegram. This makes changing numbers even easier.