Most people will probably want to buy at least one phone number. If you haven't already, first log in to the OnSIP Admin Portal. Next, click "Resources" to the left of your screen.  Select "Create New Resources", click "Phone Number" then "Create a New Phone Number".

You will be taken to the Resources tab, with the new resource dialog open and "Phone Number" selected.

Click "Create a new Phone Number" and you will see the new phone number dialog.

Select the Area Code and Rate Center in which you want your phone number to be located. You can pick any type of destination you wish, provided you've already set it up. You may also decide whether or not to reject unidentified calls by checking "Block Calls Without Caller ID." If you wish you can also add a short, descriptive note.

When you're done, click "save." If everything went well, you will be shown a message saying that you've purchased a new phone number, and the phone number will appear in the Resources tab.

If you later wish to modify or remove the phone number, navigate to the "Resources" tab, and click on the phone number you wish to alter. You will be presented with the phone number details.

Click "modify" to change its settings, or click "delete" to remove the phone number. Please be careful when deleting phone numbers as they cannot be recovered.

Once you've purchased a phone number, you can assign it to anything that has an "Extensions & Phone Numbers" setting. Just click modify, choose "Phone Number" and select your phone number from the list.