How to Set an iPhone Text Message Signature
Text message signatures are common features on phones of all different types. These signatures allow you to add your name or personal information to your message each time that a text is sent. Wit the iPhone, you can set your message signature in just a few seconds from the phone's main menus. Once set, you will be able to send your signature message to every contact every time.
Tap the "Settings" tab on your iPhone homepage.
Select "Messages" in the "Settings" tab and tap on "Signature."
Type in your signature message using the iPhone keypad and click "Save" when you are finished.
Click "Done" in the text message settings and your signature will be saved.