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) WHEN did this issue first begin.
2) Can you still get a dial tone and make OUTGOING calls?
3) What phone service provider (phone company) you have for this phone line?
4) Do you have ANY other phones (NOT part of this system) attached to this same phone line and if so, are they working properly?
Sorry for any delay - it does take a bit of time for your messages to get to me.