When you get a new cell phone number, head to the Mobile Settings page on Facebook to change your information. Registering a cell number with Facebook makes it possible to send and receive updates using text messages and, if you choose, share your number with friends. If you want to give your friends only your new number without setting up texting, change your number through the profile on your Timeline instead.
Log in to Facebook, open the drop-down menu on the top bar and click "Settings." Press "Mobile" to see the cell phone currently registered to your account.
Click "Remove" by your old cell number, and then press "Remove Phone." You don't have to remove your existing cell phone number if you would rather have multiple numbers listed. For example, if you have a free texting number or a second cell phone for work, you can add it to Facebook without deleting your primary number.
Press "Add a Phone." If you already have another cell number listed, click "Add Another Mobile Phone Number" instead. Choose your region and cell carrier and click "Next."
Send a text containing the letter "F" to the phone number Facebook displays. Most phone carriers in the United States use the number "32665," but a few carriers have alternate numbers, so check the number on the screen.
Type the confirmation code you receive via text message into the box on Facebook. Uncheck the option to share your phone number with friends or the option to receive updates through text messages, if you want, and press "Next." Enter your Facebook password to confirm your identity, if prompted, and the Mobile Settings page will refresh to display your new number.
To share a cell number with friends without setting up texting, head to your Timeline. Click "Update Info," choose "Contact and Basic Info" and click "Edit" by your cell phone number. If you don't have a cell number listed, click "Add a Mobile Phone" instead of "Edit." When you add a phone number through the Timeline, Facebook texts you a confirmation code. Enter it on the Mobile Settings page to verify your number. If you want to turn on texting later, click "Activate Text Messaging" on the Mobile Settings page.
Return to the "Contact and Basic Info" tab any time you want to change who can see your number. Click "Edit" by your cell phone number, open the audience selector and pick "Public," "Friends," "Only Me," "Custom" or one of your friend lists. This method works regardless of how you added your cell number.
To avoid fees if you don't have unlimited texting, decrease the maximum number of texts Facebook sends per day on the Mobile Settings page. You can also change when you want Facebook to text you, or set the option to "Never."