This isn't a VB
or a database question. Look into SMS provider gateways. You will likely use VB
and/or sql to decide how, when and what SMS you will send, but you're likely looking at a web service or other external asset for actually sending the SMS.
Another possible option is availing yourself of the fact that most phones can receive SMS by simply sending them an email. There are different domains for different carriers, so you need to know what carrier a given phone number is on. For example, if they are verizon you would use "email@example.com" T-mobile: "firstname.lastname@example.org".