The exact menu names may be slightly different for different OS versions, but the basic steps still apply.
Older versions of the operating system call thisBlockedorCall Blocking & Identification.
Find the person in the list and swipe right to left across the entry.

When you unblock someone, communication is opened across the board.
you’ve got the option to’t block someone’s calls, for example, but leave texts open.
It’s an all-or-nothing deal.
If you’ve blocked numbers that way, the steps listed above won’t work for you.
Those only apply to numbers blocked on your Apple rig using the built-in options.
FAQ
Tofind out if someone blocked you on your iPhone, ask them directly.
Find the person you want to unblock and selectUnblock.