Create plugin for SMS

Hi

I would like to create a plugin for CB to send SMS to members. I would like a button like the Mass-mail button in backend.
I have the mobile numbers as a field on the profile. The result should be URL calls for the selected users in this manner:
www.smsglobal.com/http-api.php?action=sendsms&user=testuser&password=secret&&from=Test&to=61447100250&text=Hello%20world

Can someone deliver an example of a plugin that adds the button in backend ( is it possible at all?) - then I myself can create the logic for the db query and the URL call...