how local should a local phone number be?

[Brett Russell]

Okay, I think I may be overthinking this: 

Because I want to be able to track the effectiveness of different marketing campaigns I plan to use different phone numbers, but my issue is that I will be marketing to at least 3 different area code (all within about an hour of each other).  

So, is is okay if all of my local numbers are in my area code or do people recommend having the local phone number in a marketing piece match the area code of where the property is?  

Obviously I wouldn't want to use an out of state area code but is an area code from a neighboring county okay?