Hello & Welcome,
I'm Greg and will be assisting you today.
Sorry to hear of any issue you are having with your phones.
To help you with this issue, may I ask:
1) What phone service provider (phone company) you have for this phone line?
2) Can you tell me what you hear when you pick up any handset, press the TALK button, and then QUICKLY listen for the dial tone?
a CLEAR dial tone,
a series of beeps, or
a few "pulsed" dial tones - before the CLEAR dial tone?