CSRF can be used to cause denial-of-service attacks against mobile phones by
flooding the phone with SMS and service messages. 
Mobile phone service providers in Israel, and throughout the world, provide
a web interface to send SMS messages. Fortunately, they limit the SMS
sending web interface to 20 messages per day, and they also require the user
to authenticate in order to send an SMS.
Unfortunately, at-least when referring to the Israeli providers, they also
give attackers a way to send endless SMS and service messages without any
kind of authentication and with a simple HTTP request.

More information:
http://aviv.raffon.net/2007/11/22/UsingCSRFToAttackMobilePhones.aspx