When you enable Facebook's mobile phone feature you are connecting your number to your Inbox on Facebook. Essentially, what that means is every time you have activity on your Facebook Page, you will receive a text message on your phone. The text message contains the facebook alert, for example "Mike posted on your wall: Happy Bday!" or "You were tagged in Mary's Photo album". Within the text message resides a link to the page where the activity occurred.
So getting back to free text messages, when someone sends you a message on Facebook, either through IM or your Inbox, you can see the message via the text message alert on your phone. What makes this so magical, is you can reply back to the text message. Your whole conversation is captured in your facebook inbox. So if your friend is in Hong Kong and you are in Alaska, and both have enabled Facebook Mobile, then you can send text messages through facebook on your mobile phone which costs nothing (but standard rates from your provider of course).
How does this work you ask? The trick is Facebook uses a local phone number to connect the two mobile devices. That way when you text, you are texting the local number- which connects through facebook's network and then back out the other side to another local number. Pretty cool, eh?
How to Get Free Texting through Facebook
Step 1) Activate your Mobile Phone
The first thing you are going to do is login to your Facebook account. In the top right there is a dropdown arrow. IN the drop down click Account Settings. Next you will see a tab on the right hand side of the screen that says "Mobile". Click on that. You should see this screen:
Click the "Add Phone" button and you should see this screen:
Here you must select your country and service provider.
Step 2) Get your Confirmation Code
The next step is get your confirmation code. Follow the instructions on the screen...
Step 3) Select Your Facebook Mobile Preferences
Once that is complete you can edit what type of alerts you want to recieve. Just one thing to keep in mind, when your Facebook account is signed in, you may not receive text on your phone.
All Done. I hope you enjoy the free International SMS :)