Page 13 shows them to be the volume control buttons, if I am reading your question correctly.
Volume Keys: Use to adjust the Master Volume in standby mode* and the Earpiece Volume during a call. Use to adjust font sizes when viewing messages, entering phone numbers (in standby mode) or browsing menus (except for the Main menu).
I think there just to light the keypad if your in the dark and you push the two lights it will light up the keypad so you can see to text.
This question has driven me crazy, lol, I finally know what the correct answer is. I never us the qwery keyboard since I an use to texting from a flip phone and the qwery keyboards letters are so small I just text from the front keypad. So here is what I found, if you slide out the keyboard you will notice to the left button acts as a soft key and takes you to Message if you click on messaage you can text right from there so I guess its a short cut key and the right button takes you to contacts and that takes to to Favorites and all your contacts. Sorry about the misinformation I gave you last time. I ordered the I user Guide which contains all 292 pages of info and its free for the asking. In that little minnie book they give you with the phone it tells you where to send for it.