How to Change the Clock on Cisco IP Phonesby Joshua Laud ; Updated September 28, 2017
If the time is wrong on your Cisco IP phone then you will need to change the clock. The time and date displayed on Cisco IP phones is set by connection to a network time protocol (NTP) server. This means that the time is updated and kept accurate by its connection to a remote time server. If the time is wrong, it will usually be because your phone is set to the wrong time zone. To change the time clock you must choose another time zone with which to connect.
Press the "Settings" button to bring up the LCD settings.
Press the menu button next to "Clock."
Press the button next to "Timezone."
Choose your timezone from the list relevant to your area.
Enter an amount for the "minutes-offset" if you desire. Otherwise press the "Settings" button to save the new clock time.