If you park a call without specifying a park slot number, the system will assign a number based on your extension number plus a single digit. For example for extension 201, the first parked call will use park slot number 2010 if available. If you already have a parked call, the next parked call uses park slot 2011 if available and so on up to 2019.

Call park buttons can be configured to match specific park slot numbers. A call parked using that button is given that park slot number. All users with a call park button set to the same number can see when there is a parked call there and can unpark that call using their button.