Panasonic KX-TA624
  1. Use phone with intercom number 101. It will change the time for all phones.
  2. Move MEMORY switch on rear from SET to PROGRAM.
  3. Dial *#1234
  4. Dial 000
  5. Press NEXT ("Sp-phone")
  6. Press Right Arrow ("FWD/DND") four times until you see the time displayed
  7. Change the hour with the keypad
  8. Press Right Arrow ("FWD/DND") to reach the minutes field
  9. Change minutes with the keypad, if necessary
  11. Press HOLD
  12. Move MEMORY switch on rear from PROGRAM to SET.