Sitefinity does not offer this functionality out of the box. However, you can take a look at this article on how to achieve it:How to send free SMS from ASP.Net application to Mobile
. There are additional examples on how to do this available on the web.
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Sitefinity CMS Ideas&Feedback Portal
and vote to affect the priority of the items