Hello & Welcome to Just Answer,
I'm Greg and will do my best to assist you today.
Sorry I didn't see your question earlier and 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.
2) Do you have a button near the word MUTE, and if so, what happens to the word MUTE - when you tap that button?
3) Do you have ANY other phones (NOT part of the main system) attached to this same phone line and if so, are they working properly?
Please REPLY using the box below and the SEND button.