0 to ask formally for someone to do something: --
I should now like to call upon the finance director to take you through the results.
If you're ever called upon at work to give a talk, the very prospect of 'getting up there in front of all those people' can be intimidating.
call on/upon sb to do sth They called on the company to reverse its decision.
1 to visit someone, especially to sell them something: --