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) How many TOTAL cordless handsets do you have with this system?
2) What is the AGE of this system?
3) WHEN did this issue first begin or was noticed?