Addendum to the above: Here's what web site says.
Welcome to npanxx.net
The primary purpose of this tool is to lookup the NPA/NXX of the Local Exchange Company (LEC) based on the physical address provided. Users may also create an account so address queries are stored for future reference. CTG3 is a master agent for CenturyLink and Comcast Business with a focus on providing support for both incumbent telco and cable companies.
Visit PREQUAL.net to perform a ZIP code carrier footprint check for the top carriers such as CenturyLink, Comcast Business, Charter Business, Level 3, Integra, AboveNet, Time Warner Telecom, GlobaLinx, Mammoth Networks ..and more!