Bluetooth HC-05 pairing between two Arduino Mega

I want to set automatic bluetooth connection when both Arduino Mega with HC-05. How this can be made. I dont want to pair devices each time. Please help. Detailed explanation will be more helpful thanks :)

Check the Philippe Cantin blog

http://phillipecantin.blogspot.ca/2014/01/hc-05-bluetooth-link-of-2-arduino.html

http://phillipecantin.blogspot.ca/2014/08/hc-05-bluetooth-link-with-zero-code.html