Individual CodeBoxes restrict access based on an "access window" configured within the CodeBox itself. 

CodeBoxes purchased from ShowMojo since May 2016 are set, by default, to accept normal access codes from midnight to 11pm. This is explicitly to allow vendor and staff use of the CodeBoxes.

If you have older CodeBoxes, purchased your CodeBoxes elsewhere, or otherwise believe the access window was altered, consult the Change the CodeBox Access Window article to extend the length of the access window on your CodeBoxes.

If you need after-hours access for vendors and staff, but want better time-based control over when prospects have access to the CodeBox, please consult the Extra Security and Notification When a Prospect Accesses a CodeBox article.