>> I'm wondering however how they can call from a number that is not yet in service?

The number was spoofed (i.e., faked).  See this article in Wikipedia for more information:
http://en.wikipedia.org/wiki/Caller_ID_spoofing  .

Got a call from these people wanting to check my roof due to recent bad weather and high winds. After thinking about it I called back to cancel and got a message saying that this number is not yet in service.  An obvious scam. I'm wondering however how they can call from a number that is not yet in service? Also wondering why so many of these numbers are coming out of the Waco/Temple area??????

phone calls with no one on line when picked up.