Everybody: Anyone on Telegram can call you.
My Contacts: Only people in your Telegram contacts can call you.
Nobody: No one can call you via Telegram.
Exceptions: You can specify "Always Allow" or "Never Allow" for particular users or groups.
"Last Seen & Online":
"Who can see my last seen & online telegram number database status?" You can choose:
Everybody: Everyone on Telegram can see your last seen status.
My Contacts: Only people in your Telegram contacts can see it.
Nobody: No one can see your last seen status.
Exceptions: You can add specific users to "Always Share With" or "Never Share With."
Important Caveat: If you hide your last seen from someone, you also won't be able to see theirs.
"Profile Photos":
"Who can see my profile photos?" You can choose:
Everybody: Everyone on Telegram can see your profile picture.
My Contacts: Only people in your Telegram contacts can see it.
Nobody: No one can see your profile picture (or only a tiny, default avatar).