Look for available lines first
Start by reviewing the phones on your account. It’s possible you have 1 or 2 spares that you can assign to a new person. They may have been devices used by people that have recently left, and their old phone number and/or device can now be reassigned. If you do have these, identify the phone number and the device assigned to this number. If you have conducted an account audit or review monthly billing you should know which lines are eligible for upgrades.
If you can’t find a spare line can contact the IT Department to find an available line