Adding a new fax number to a sub account is quick and easy.
Note: You must provision new numbers from within your master account. If you try to provision a new number while managing a sub account it will throw an error.
Just follow these steps:
Sign in to your web application at your custom portal address
Click on "Numbers" on the left panel
Click on "Get Numbers" in the top right
Use the drop down to choose search type
Enter the correct search by information (area code for prefix, etc.)
Check the boxes of the number(s) you want to add
Scroll down to the bottom and select Order Number(s)
Your new number will now be available in your account.