Toggle "Sync Contacts" OFF.
Then tap "Delete Synced Contacts". This ensures Telegram does not continuously upload and store your device's address book, preventing automatic links to your real-world contacts.
Use a Username: Always set a username (@YourUsername) in Settings > Username. Share this username instead of your phone number for connecting with new people or in public telegram number database groups/channels. This is the most common and privacy-friendly way for others to find and message you without knowing your number.
Review Other Privacy Settings: While not directly about your phone number, consider reviewing other settings under Privacy and Security like:
Last Seen & Online: Set to "Nobody."
Profile Photos & Videos: Set to "Nobody" or "My Contacts."
Forwarded Messages: Set "Who can link to my account when forwarding my messages?" to "Nobody."
Calls: Control who can call you.
Enable Two-Step Verification (2FA): Go to Settings > Privacy and Security > Two-Step Verification. This adds a password to your login process, providing a critical layer of security even if your phone number is compromised.
By carefully configuring these settings, you can maintain a high level of privacy regarding your phone number on Telegram, controlling precisely who has access to it and how you can be found.
Their Privacy Settings Matter: You can only add someone as a contact via their phone number if their Telegram privacy settings allow them to be found by number (Settings > Privacy and Security > Phone Number > Who can find me by my number?). If they have set this to "Nobody," you won't be able to add them this way, even if you have their number. In such cases, you would need their Telegram username (@username).
No Notification to Them: Telegram generally does not notify a user when you delete them as a contact or re-add them. Notifications typically occur when a contact joins Telegram for the first time.
Chat History Remains: Even if you delete and re-add, your past chat history with that person is still there.