My application sends SMS messages to people, but the numbers entered in as their cell phone are sometimes land lines (this is user error or the user not really knowing if the contact number they have is a cell phone or landline.)

I found a few websites that can tell me if a number is a landline or cell phone, but they do not offer programatic API's. Is anyone aware of a way a web application can figure out if a number can receive SMS messages?

I guess a test SMS message is one way, but my current SMS gateway fails hard when it gets a landline number and doesn't tell me the landline number it tried to send the SMS to. I'll follow this up with my carrier, but I would love an easy way to let the user entering phone numbers in if they are a landline or cell number.

Update: There are ways to figure this out. Take a look at http://www.phonevalidator.com, they can query a phone number and figure out if it is a landline or cell phone.