How to send SMS in Java
(Disclaimer: I work at Twilio)
Twilio offers a Java SDK for sending SMS via the Twilio REST API.
if all you want is simple notifications, many carriers support SMS via email; see SMS through E-Mail
There is an API called SMSLib, it's really awesome. http://smslib.org/
Now you have a lot of Saas providers that can give you this service using their APIs
Ex: mailchimp, esendex, Twilio, ...