How to set the ringtone of fixed telephone?

In the on-hook state, press "Setup" key, press 2, then press 1, press "Search Up and Down" (* and #) keys to select ringtones (more than ten ringtones are optional), press "Setup" key to confirm, and press "Delete" key to return to the previous item; In the on-hook state, press the "Settings" key, press 2, and then press 2 to enter the VIP ringtone selection. The setting method is the same as above. In the on-hook state, press the setting key, press 2 and then 3 to enter the ringtone volume adjustment, and press the up and down search keys to adjust the volume.