I use the Contacts app with this icon
and write something in the search field to find a contact.
I click the contacts name and come to this screen:
Now, I have found no way to edit the phone number. Clicking inside the box with the green caller will call the contact.
Clicking the menu will give me the menu alternatives: Delete, Join, Add to Home screen.
There is no text anywhere that sais "edit contact" or the like.
Clicking the contacts name will not result in anything. Clicking the contacts photo will show it bigger.
Long clicking inside the box with green caller will popup a menu with the alternatives "Forward contact" and "Copy to clipboard".