Which company owns that exchange?

[ZaphodB]

http://www.nanpa.com/nas/public/assi...CodeQueryModel

The North American Numbering Plan Administrator assigns area codes (called NPAs in telecom jargon) and exchanges (called NXXes in telecom jargon) in the United States.

This tool tells you which telecom company originally was assigned the exchange. For example, 310-920-XXXX is T-Mobile USA. Most likely, a 310-920-XXXX number is T-Mobile and therefore would be mobile-to-mobile from other T-Mobile phones.

Of course, since we have LNP and WNLP (number porting for landlines and wireless phones), there is no guarantee that a given telephone number in the exchange is necessarily assigned to that company, so insert the usual disclaimer about WirelessAdvisor.com and NANPA not being responsible for damages if you use this tool.

[Andy]

This might cost you a little time, but if I'm not sure whether a number is FREE M2M from my VZW phone I enter the questioned number in the mailbox system(basically "send" them a message, then cancel it) to see if they have VZW, and are hence free to call, or not.