It then shows you which of your phone contacts are on Telegram, typically adding them to your in-app Telegram contact list.
It can also notify you when new contacts from your phone's address book join Telegram.
Part 1: How to Enable Contact Sync
If you want Telegram to automatically find your friends and add them to your in-app contact list:
Open the Telegram app on your smartphone or tablet.
Go to Settings:
On Android: Tap the ☰ (three horizontal lines) icon in the top-left corner to open the main menu, then select Settings.
On iOS: Tap the Settings icon at the bottom-right corner of the screen.
Navigate to Privacy and Security: Scroll down the settings menu and tap on Privacy and Security.
Find the Contacts Section: Scroll down within "Privacy telegram number database and Security" until you find the "Contacts" section.
Toggle "Sync Contacts" ON:
Find the option labeled "Sync Contacts" and tap the toggle switch to turn it ON. It will typically turn blue or right-aligned.
If this is your first time enabling it, Telegram might ask for permission to access your device's contacts. You must allow this for the feature to work.
Allow Time for Sync: It may take a few moments for Telegram to upload and match your contacts, especially if you have a large address book.
Part 2: How to Disable Contact Sync
If you prefer that Telegram not automatically upload and add contacts from your phone's address book:
Go to Settings: (Refer to Step 2 in Part 1).
Navigate to Privacy and Security: (Refer to Step 3 in Part 1).