If you have contacts in your Telegram account which you don't recognize, you have most likely logged in on another person's phone – and uploaded their contacts to your account by accident.
You can wipe all previously uploaded contacts from Telegram and then re-upload them from your current device.
On your Telegram mobile app, use the 'Delete Synced Contacts' button in Settings > Privacy and Security (' > Data Settings' if you're on iOS). To re-upload your up-to-date address book, make sure the Sync Contacts toggle is turned on.
Note: If you need to use someone else's device to log into your account, make sure to disable Sync Contacts when entering your phone number on the login screen. This will prevent the local phonebook from being imported to your account. Telegram will also warn you before importing an unusually large number of new contacts.
"Contact Sync issue: Certain phone numbers do not appear as Telegram users on my account, even in the 'Invite' list. I've deleted my account and reset everything, but the issue persists for a year. Other accounts can see these users fine. It's a server-side mapping error for my phone number."
Log in here to report bugs or suggest features. Please enter your phone number in the international format and we will send a confirmation message to your account via Telegram.