Access is determined by the type of lockbox being used. Some require an electronic "key" with the proper codes for opening, and to obtain the key inside the lockbox for unlocking a door. To use such a "key" one must be a member of a local real estate association, in good standing, and have a current subscription to the local MLS. Users of such electronic devices can be realtors, appraisers, home inspectors, loan officers, property managers, and/or any other real estate business related person/entity.
Another type of lockbox used is a combination lockbox. Similar to a standard combination lock, whereas anyone knowing the combination and/or numeric sequense to open the box can obtain the key inside for access to the interior of a property. This type of lockbox does not require specific licensing and/or affiliation to any professional organization to use. Many times the code is included in the property description of the listing, or some part of the listing, by the listing agent.