Call on

To visit (a person); to pay a call to.

"I really should call on my aunt more often."

To select (a student in a classroom, etc.) to provide an answer.

"He sat there, baffled, hoping nobody would call on him."

(also call upon) To request or ask something of (a person); to select for a task.

"The king called on his subjects to take up arms and defend the kingdom."

(also call upon) To have recourse to.

"Exhausted, he called on his last ounce of strength."