The NBA is planning to experiment with a coach's challenge system on referees' calls during Las Vegas Summer League.

Officials are still working on what mechanism coaches will use to trigger a challenge and what the parameters are, but they will not use a flag, sources said. Both the NFL and Major League Baseball have coach's challenge systems.

NBA executive vice president of basketball operations Kiki VanDeWeghe had indicated Sunday on SiriusXM NBA Radio that the NBA hoped to experiment with a challenge system during summer play.

"The competition committee has been trying to figure out how we actually do this, because there's some complications. It's not quite as simple as you might imagine. We've had it in the G League for a number of years now and it's been very effective. We're going to try it in a very limited form in Summer League and we're going to see how it goes. We're going to let everybody look at it," he said, according to USA Today Sports, which transcribed his comments.

Over the past several years, the league has used summer league and the G League to test out rule changes, including adjusting goaltending rules and expanding officiating crews.

The league has steadily increased the use of instant replay over the last decade, routinely adding the types of plays that can be reviewed and triggers that allow officials to go to the monitors.

No matter how the testing goes in Vegas, it is unlikely the NBA would adopt any new challenge rules for next season, VanDeWeghe said.