Click on your profile icon.
Click on the availability drop down menu.
Click on Manage Status
Select the three dots underneath your profile icon.
Select the new option.
Give your new status a name.
If you want to pre-define what device will be used when making calls from your client (as opposed to manually selecting one on the main page), select the device here.
Define what devices you want to ring for incoming calls.
Select the done button to save.
Your new status will now be available to choose from.