'To call upon' definitions:

Definition of 'To call upon'

From: GCIDE

Call \Call\, v. i.
1. To speak in loud voice; to cry out; to address by name; -- sometimes with to. [1913 Webster]
You must call to the nurse. --Shak. [1913 Webster]
The angel of God called to Hagar. --Gen. xxi. 17. [1913 Webster]
2. To make a demand, requirement, or request. [1913 Webster]
They called for rooms, and he showed them one. --Bunyan. [1913 Webster]
3. To make a brief visit; also, to stop at some place designated, as for orders. [1913 Webster]
He ordered her to call at the house once a week. --Temple. [1913 Webster]
To call for (a) To demand; to require; as, a crime calls for punishment; a survey, grant, or deed calls for the metes and bounds, or the quantity of land, etc., which it describes. (b) To give an order for; to request. "Whenever the coach stopped, the sailor called for more ale." --Marryat.
To call on, To call upon, (a) To make a short visit to; as, call on a friend. (b) To appeal to; to invite; to request earnestly; as, to call upon a person to make a speech. (c) To solicit payment, or make a demand, of a debt. (d) To invoke or play to; to worship; as, to call upon God.
To call out To call or utter loudly; to brawl. [1913 Webster]