Okay, first, please tell me you’re gonna have your customers opt in for this service. Texting charges can be pricey for some users.
Second, try Teleflip‘s free service. You can send text messages to any cell phone in the US by sending email to (area code + phone number) @ teleflip . com.
Whoops, Teleflip is out of business.
Try looking around for a similar service then.