Another set of phrases today having combination of single verb with different prepositions.

Call at means to call at some place
I called at my friend’s place to confirm the news of board result.

Call for means require or demand
The labour is calling for a strike tomorrow.
The situation calls for an emergency action.

Call on means to invite a person
The boss has called on all the employees for an important meeting.

Call off means to cancel or abandon something already started or yet to begin.
The match was called off due to heavy rain.

Call up means simply to telephone.
He called me up to tell about tomorrow’s holiday.