Facebook lets you share status updates, photos and links from your mobile phone via SMS. In addition,
Facebook sends SMS notifications to your mobile phone when you receive Wall comments, someone replies to a comment you made on someone else's posted item, a friend messages you and other events, depending on your notification settings. When you receive a
Facebook SMS notification on your mobile, you can reply in a comment or private message. The message you send will automatically be routed to the proper location on Facebook.
Open and view a received text message from Facebook on your mobile phone.
Scroll to the bottom of the message and look for the words "Reply to Comment." If you see those words, you can reply.
Press "Reply" on your mobile phone or the equivalently labeled function.
Key in a reply and send the message.