Yes. In the Clients tab, scroll to the bottom to find the Add Client bar. Add the necessary information (only First Name box is mandatory to proceed). Click Add Client.
You will now see a generated Client page. The system automatically generates a 6 digit Call In Pin (for information on changing that, click here). You will need to assign the proper Testing Profile and Call in Window. Aside from name and call in PIN, these are the only two mandatory sections. You will see on the left hand side below their name a pull down option labeled Active. By default, it will say No. Keep this at No until you are ready to make them live in your system. Once you are ready, simply change that option to Yes. Always hit Save after any modifications.