"be called upon by" is a correct and usable phrase in written English.
It is commonly used to describe a situation where someone is asked or required to do something, often in a formal or unexpected manner. Example: The new employee was called upon by her boss to give a presentation on her first day of work.
In the course of your work, it's likely that you'll be called upon by clients to answer questions about the greater lending market, or even aspects of personal finance somewhat unrelated to a reverse mortgage.
But anonymous sources must be aware that they may be called upon by our judicial system to identify themselves.
And it was a great honor to be called upon by Sandra Banning, the mother in the case.
It said shipments of international food aid support 33,000 US jobs and help maintain a merchant marine that can be called upon by the department of defence in cases of war or national emergency.
While the helicopter's primary mission will be policing this stretch, which is Amtrak's busiest, the helicopter could be called upon by the Amtrak police in other regions, Ron Frazier, the railroad's police department chief, said.
Serfs could be called upon by the state to pay taxes, to perform corvée labour on roads, and to serve in the army, but slaves usually were exempt from all of those obligations.
I recall being called upon by a group of my leftish mates to go and march for the printers at Wapping.
The team work entirely on a voluntary basis, leaping to action on specialised rescue boats when they are called upon by local fishermen.
Douze and Rosa-Salas describe Mami Wata as being "called upon by those pursuing wealth, wisdom, emotional guidance, and sexual liberation.
Despite two failed bids for the presidency and a near-fatal aneurysm, "Call Me Joe" Biden continued to live the life of a happy successful man when he was called upon by newly crowned democratic presidential candidate Barack Obama to serve as his Vice President in 2008.
The enquiry was chaired by Professor (now Lord) John Krebs, and was the third such expert review since 1980: a pattern which has continued subsequently, with three further groups of 'independent experts' having been called upon by successive UK governments to the present day.
