Is there a free API or some other way to determine what carrier a cell phone number is registered with?
I'd like my application to broadcast text messages without them picking their carrier from a list.
UPDATE: Interestingly, a coworker found the answer: http://developer.whitepages.com/
UPDATE2: Well the whitepages license agreement is so restrictive that you can't build an app for it. Any other ideas?
Your biggest problem is that people can now take their numbers with them. So while in the past cell phone carriers had blocks of phone numbers, and probably still do, there's no reliable way to map a specific cell number to a certain carrier.
What I do is just screenscrape off a website that does a 'whois' on the number
You should note that the way to figure out which carrier a number belongs to will be country-specific (though, some countries might use the same scheme, but I'm not sure - I've worked with both the norwegian and swedish portability databases and they're quite different api-wize - and require vpn + authentication).
The information is, at least here, not available to the public - I've seen service providers, network operators and information providers (as in yellow pages) that have access.
But otoh, wouldn't a proper sms gateway service do this for you?
Data24-7 offers an API for looking up the carrier for wireless phone numbers. It also returns the email addresses to send SMS and MMS messages to the phone. It's not free, it's $12 per month and $0.006 per lookup.
The link is: http://www.data24-7.com