This article is talking about the Supra Blue electronic boxes that are placed on listings, usually on the front door. The lockbox holds the key to the house and will open for an real estate agent when the agent has updated their password to get into the house. As the agent requests a password update over their telephone modem, it also submits what lockbox and listing the agent has seen and what time they entered the home.

On each listing, the owner has spelled out how they want the house shown. Most sellers who have a lockbox want the agent to give them a courtesy call before showing the home. Courtesy call does not mean that the agent has to make an appointment, but it does mean that the agent must call the phone number on the listing before they show the home to let the owner know who they are, what company they work for and when they will be showing the home.  So, in most cases, the agent does not have the ability to show just any home anytime.  Time is needed to call the owner and follow the showing instructions. 

Some homes require a 24-hour notice and others are appointment only which means that the owner must call the agent back to arrange a time to see the home or put the lockbox out for the agent. 

Some vacant listings say to show anytime and they do not require a courtesy call.

Lockboxes will open between 9 a.m. and 9 p.m. only.

Some other professions are allowed a Supra lockbox key such as inspectors,
stagers, appraisers and a few others.