do you ave a answering machine? unplug it and see if the problem goes way.

actually the best test is this.

unplug home at nid, run a cheap brand new 25 foor cable from nid to indoors and see if your problem, run wire in thru a window.

if the phone now works, the problem is your indoor wiring.

if it fails to work, its the phone companies problem

phone reps always blame your indoor wiring

things that cause phone troubles like your having.

old wiring from central office to your home. rain water shorting things somewhere

phone companies arent spending much money to maintain the copper infrastructure. they just want profit, service comes last......