IT WON'T quite be the voice of God, but umpires will have the voice of 'Giesch' in their ears during next year's NAB Cup.

In a trial rule for the 2013 pre-season competition, umpires coaches - director of umpiring Jeff Gieschen, plus Rowan Sawers, Hayden Kennedy and Bryan Sheehan - will be allowed to communicate with on-field officials via radio at any time during matches.

The idea was suggested by Melbourne sports performance director and former Adelaide coach Neil Craig, who spent a game in the umpires' box at the invitation of AFL football operations manager Adrian Anderson in 2012.

Craig witnessed the coaches talking to umpires during score reviews and at breaks, and asked why it couldn't happen more often.

"He was saying, 'you could've helped that umpire by alerting him to this or that, or telling him he needs to adjust his positioning; why don't you talk to them?'" Anderson said.

Anderson stressed the umpires wouldn't be instructed or influenced on specific decisions.

The feedback would be more about taking advantage of the coaches' whole-of-ground view.

"It wouldn't be telling them what decisions to make or anything like that, it'd just be in terms of their positioning, or anything they might need to look out for," Anderson said.

"They might say, 'you need to keep your eyes on what's happening in the goalsquare'.

"That's something they could potentially do.

"Whether that's a good thing or not, that's what the NAB Cup's for - to enable things like that to be trialled."

UmpiresUmpire Matthew Nicholls listens to a goal review decision in 2012. Picture: AFL Media

And Anderson said all communications between umpires and their coaches would be available to broadcasters.

"We'll do it in a way that's transparent, so that people can listen in so there can't be any integrity issues," he said.

Other NAB Cup trial rules announced this week were:

•    A cap on interchanges of 80 per team, per game
•    Nine-point supergoal from outside 50 metres
•    Boundary and goal umpires allowed to pay holding and high contact free kicks
•    Free kick against players who kick or handball out of bounds

In August, the Laws of the Game committee floated the idea of restricting players to set zones at centre bounces, but that suggestion has not been adopted.