Read our article HERE on the differences between Campaign and Direct Dial Numbers.  Make sure that you are configuring the correct type of number for your inbound/outbound process.  

1.  Go to Settings>Phone>Phone Numbers and click on Manually Add Phone Number.  

2.  Search for the Area Code you would like to purchase and you will be given a list of all available numbers.  Check the "Agree" box and purchase a number.

Note:  If no numbers pop up, there are no numbers available for purchase with that area code.  Check back later, or try a nearby area code.  

3.  Follow the template below to properly configure your Campaign number.