How to Disable Facebook SMS Subscriptions
Facebook allows you to subscribe to receive text messages, also known as Short Message Service (SMS) messages, on your phone when people connect with you via the social networking website. If you do not want to receive the text messages, you can unsubscribe completely or customize the instances when Facebook sends you a text message. You can unsubscribe by sending text messages to Facebook or by visiting its website to customize your settings.
Text "off" to Facebook to stop Facebook from sending any SMS notifications to your phone. Visit the Facebook Text Messages page to look up the number to which you must text "off" to unsubscribe from all Facebook texts.
Turn off all Facebook texts by changing your mobile settings on Facebook. Click on "Account Settings" in the Facebook "Account" menu, and click the "Mobile" tab. Turn texts off in the "Facebook Text Messages" section.
Change your notification settings if you want to limit the types of SMS messages you receive. Click on "Account Settings" in the "Account" menu, and open the "Notifications" tab. Check the items you want to receive SMS notifications about, and leave unchecked the items you do not want to receive texts for. For example, you can have Facebook send you SMS messages when someone sends you a private message or writes on your wall but not when people confirm your friend requests.
Text "Unsubscribe" to disable SMS subscriptions to a single friend's status updates. Send the message when you receive a notification that that particular friend has posted a new status.