The phrase "if called upon" is correct and usable in written English.
It is used in sentences to mean "if asked or required to do something". For example: "I will be ready to help if called upon."
If called upon, heavy equipment will be amassed there, then sent to New York.
Lacy will also develop into an effective three-down back if called upon to do so.
Ordinary Brazilians hope that Mr Fachin, if called upon, will be equally fearless.
If called upon, he said, "They could do an entire ballet on their hands.
I'm certainly prepared to provide my services and life if called upon.
But I'd be ready to lead the country if called upon".
It is a man's right to decline to play for his country if called upon.
The day when an architect could, if called upon, carve his own stone was long gone by the 1930s.
The Detroit Symphony proposal would require the orchestra musicians to carry out a host of nontypical activities, if called upon.
Aloise suggested that the Teamsters, if called upon, would be willing to take over the suit and continue to litigate.
Tomlin described the Steelers' philosophy as "every man in the helmet," that he expects every player to make decisive plays, if called upon, at one time or another.
