To set date:
Leave the handset in the cradle.
Press the Intercom key + # 651 (Listen for the confirmation tone).
Enter the date in the YYMMDD format.
Press the # key. (Listen for the confirmation tone)
To set time:
Leave the handset in the cradle.
Press the Intercom key + #652 ( Listen for the confirmation tone).
Enter the time in 24 hour clock format. (HHMMSS)
Press the # key. Listen for the confirmation tone.