I have an application where people can give a phone number and it will send SMS texts to the phone number through EMail-SMS gateways. For this to work however, I need the phone company of the given number so that I send the email to the proper SMS gateway. I've seen some services that allow you to look up this information, but none of them in the form of a web service or database.
For instance, http://tnid.us provides such a service. Example output from my phone number:
Where do they get the "Current Telephone Company" information for each number. Is this freely available information? Is there a database or some sort of web service I can use to get that information for a given cell phone number?
Best Answer
What you need is called a HLR (Home Location Register) number lookup.
In their basic forms such APIs will expect a phone number in international format (example, +15121234567) and will return back their IMSI, which includes their MCC (gives you the country) and MNC (gives you the phone's carrier). The may even include the phone's current carrier (eg to tell if the phone is roaming). It may not work if the phone is currently out of range or turned off. In those cases, depending on the API provider, they may give you a cached result.
The site you mentioned seems to provide such functionality. A web search for "HLR lookup API" will give you plenty more results. I have personal experience with CLX's service and would recommend it.