In order to subscribe to your friends’ status updates, you must first make sure you have activated Facebook Mobile Texts on your mobile device. To activate Mobile Texts, go to the Mobile tab on the Account Settings page, click "Register for Facebook Text Messages," and complete the steps that follow. If your carrier is not listed in the drop-down menu it means that it is currently not supported for Facebook Mobile Text. We encourage you to talk to your mobile operator to let them know that you are interested in this service.
After you’ve activated Facebook texts, you can subscribe to a friend’s status updates by going to his or her profile and clicking the "Subscribe to SMS updates" link beneath the profile picture. You can also manage your subscriptions from the SMS Subscriptions tab of your Edit Friends page.