Phrasal Verb: Call on

Meaning: Ask for help

Example: The President CALLED ON the wealthy countries for financial aid after the floods destroyed much of the country's agriculture.

Meaning: Visit

Example: As we were in the area, we CALLED ON my sister-in-law.

Meaning: Challenge

Example: He CALLED the speaker ON several mis-statements of fact.

Meaning: Ask someone to do something, especially to speak in public. (Formal)

Example: I now CALL ON the other party to give their account of what happened.