Add Dial prefix
DIla prefix is usefull when you need to hide your phone number - this could be one of the swipe actions. Let's say you want to hide your number - U set dial prefix to #31# so when you swipe it dials #31#_number_you_call_ - that way remote party will get Unknown Caller (Or Private Call). So - no dial prefix your Caller ID is visible - with Dial Prefix it's invisible.
It can be also used for other purposes.