On Wed, Jun 6, 2012 at 1:39 PM, Patrick Avella me@patrickavella.com wrote:
As long as you know the carrier a cell number uses, you can send it an SMS via email.
This solution isn't drupal specific, but here's a general how to (first link I found on google)
And using this you should ask the user for the Cell phone number and their plan provider giving a select list of known providers. You cannot really determine the provider who provides the service from the phone digits because of number porting.