accidentally found this trick while using my new phone.
While at the main menu hold down the "-" volume button to quickly put the phone into vibrate only mode.
Hold the "+" to place it back to the main ringer volume. Just thought I'd share as this is my first texting phone.
Had this phone for about 2 weeks now and I'm very happy with it.
Call quality, ease of texting and battery life are more than adequate for my daily use.