To set date: 1- From main/reception telephone, leave the handset down and press #651 2- Enter the date YYMMDD 3- Press # 4- Press the speakerphone key to finalize setting. To set time: 1- From main/reception telephone, leave the handset down and press #652 2- Enter the time as HHMMSS in the 24-hour clock format 3- Press # 4- Press the speakerphone key to finalize setting.