home phone

Check your connections... if everything looks good call to schedule a service appointment. 

If the tech discovers the issue is your equipment or inside wiring you can be billed minimum $99.

Do you have tradition phone line or VOIP line?

IF ATT PHONE, IS THE PHONE LIGHT SOLID ON THE GATEWAY?

If this is a traditional landline (POTS) test from the NID with a known working corded phone and if still bad report to the phone company.