Telephone numbers?

Is there a web cite or resource where I can look up what company provides different telephone exchange numbers?

• I often have to contact telephone providers regarding various telephone exchange numbers (the three numbers that follow the area code). Is there a web cite or other resource out there that would tell me the name of the phone provider ( and preferrably a phone number and address ) that supplies that exchange?

• Answer:

  http://www.yellowpages.com/ it is a magical website.