After changing the name of a user the caller Id may still display the old incorrect name. This is because your phones get their caller ID from their directory so their directory needs to be re-synced so it can be updated. To do this you need to log into your portal with an office manager account. Click on the inventory tab (1), then phone hardware tab (2), click on the top most checkbox (3) to select all your phones and then click on the reboot button (4).

This will open up the reboot phones window. At here click on the reboot phones button(1) This will reboot your phones one by one so they pull down the new directory.