Share Your Username, Not Your Number: Whenever possible (e.g., on social media, professional websites, in public groups), share your Telegram username instead of your phone number. People can find you and start a chat by searching for your username, and your phone number remains hidden (if your privacy settings are configured as above).
IV. Control Contact Syncing
This feature helps you find contacts but can also involve uploading your address book.
Disable "Sync Contacts" (if desired): Go to Settings > Privacy and Security > Contacts and toggle "Sync Contacts" OFF. This prevents Telegram from continuously uploading new contacts from your telegram number database device's address book.
Delete Previously Synced Contacts: If you've ever had sync enabled, tap "Delete Synced Contacts" in the same section. This removes any contact data Telegram may have stored from your phone's address book from its servers.
V. Monitor and Manage Active Sessions
Regularly check where your Telegram account is logged in.
Review Active Sessions: Go to Settings > Devices (or Settings > Privacy and Security > Active Sessions). This shows all current logins to your Telegram account, including location and device type.
Terminate Unknown Sessions: If you spot any unfamiliar or suspicious devices/locations, immediately select them and tap "Terminate" or "Terminate Session." This remotely logs out that device.