Hello & Welcome to Just Answer,
I'm Greg and will do my best to assist you today.
Sorry to hear of any issue you are having with your phones.
To help you with this issue, may I ask:
1) The FULL Model Number of the phone system you are working with? If this is a cordless system, that model should be printed on a sticker on the bottom or back of the MAIN base and START with KX-TG.
2) Have you tried pressing the MENU button, and THEN the # key (hash or pound), then the 2 1 7 code?
I only ask because that is the "normal" use when punching in "direct commands".