Sorry to hear that the home phone service is giving you difficulties! There are a few variables that might be causing this to happen.
1) Are you in an area with adequate coverage? (All green lights on your box)
2) Is your box near a window and away from the microwave? (I say this because when I had my box near my microwave my calls were affected)
3) Have you by chance tried with a different phone attached to the box to see if there is any improvement?
As always you can call customer care and have them perform some additional troubleshooting with you If you are able to call from your cell phone instead of the home line that would be best.
Remember - You have a one year warranty on the home phone (maybe the box is defective) If needed the box can be exchanged (as long as it is not physical or liquid damage) and that would all be done over the phone with client care.