SMSMessenger
SMSMessenger, is an intergrated API for ClickATell.com. It allows the end user to send SMS messages from their desktop PC, without much effort. Not only does it allow for Single SMS messages to be sent, but it can also send in bulk. Between two ranges of numbers to increase the range your message can be sent. Allowing for in theory to send an SMS to every person in your country. Please be aware of the countries offered by ClickATell.com, as these are all that is supported.