No dial tone - telephone line connecting the base unit to the modem was bad
We moved to a new home and initially all we had was internet after the line was connected to the house. Did my in-house troubleshooting to verify the cables were good and then got telephone support to get the correct settings at COMCAST's end which fixed that. Still had no telephone dial tone though (X1 Triple play package). Got transferred to the phone section and the representative there spent a good 45 minutes trying various things, which in the end resulted in a steady light on the modem for the telephone. With that confirmed, I figured the problem was on my end and sure enough, after replacing the telephone cable that runs from the base unit of the wireless telephone to the modem - A DIAL TONE !!!!!!!!!!! This is the first time I've had a telephone cable fail, but that was in fact the culprit.
Thought I'd pass this on just in case it might happen to someone else - beats buying a whole new phone and/or having to bring in a technician and pay for a service call.