As a result of Senior Constable Ricky Wayne Colbron's report that the subject was on school grounds and "may or may not be a police officer", an urgent job was broadcast on police radio.

Prosecutors said Colbron knew the identity of his off-duty colleague, who had never left his car while waiting for school to finish.

On Friday, Sydney magistrate Erin Kennedy found Colbron guilty of making a false representation resulting in a police investigation.

She placed the man in his early 30s on a 12-month conditional release order but recorded no conviction.

The radio call drew several officers in the direction of the Malabar primary school until some alert local police recognised the description.

While the job was downgraded within minutes, armed plain clothes officers approached the car of the off-duty colleague, who raised his hands in the air.

"There was a lot of families waiting around for their kids so it was pretty embarrassing," Leading Senior Constable Michael Ide said on Thursday.

The hearing heard a chief inspector, who was also a friend of L/Sen Const Ide, sought an inquiry into the call.

"(I found it horrible) a person would try and set up his work colleague," Chief Inspector Paul Fownes said.

He didn't inquire into his mate's gun-carrying, saying he was "quite comfortable" with the conduct of the officer who was at that time authorised to take his weapon home.

The magistrate was played a tape of the tip-off call.

"I'll send an urgent job in case it's not a police officer," the operator told the unidentified Colbron.

"Ah OK," he replied.

His lawyers argued everything in the call seemed to be true, and sought to suggest the gun-carrying could be misconduct.

The hearing was told Colbron received advice from two officers, including one in the force's internal investigation unit, that the Police Assistance Line was a method of anonymously reporting possible police misconduct.

Australian Associated Press