My landline phone rings but no dial tone,and says no line

SOURCE: Phone doesn't ring, no dial tone.

Try switching the battery wilth a know to be
good battery

SOURCE: no dial tone - phone rings for incomming call but I can't hear or talk

This can be a problem with your handset.
Have you tried a different phone in that same jack?

SOURCE: I pick the phone up, no dial tone. Display says

We called the phone company.....There was a problem up on the telephone pole. They fixed it, no charge.

SOURCE: no dial tone and "line in use " message

Try the simple things first. Try a different phone. In my case, I had the phone company check - outside was fine. After two hours my phone worked. I figured out what happened in my case. Both phones were dead (battery). I think one died with the phone off the hook. once the phones were fully charged, the phone worked.

SOURCE: continuous dial tone on phone line

There are two possible answers to this problem. The first thing is to check on the cordless phones, is a 2 way switch, one setting is for DP=Dial pulse (setting for old rotary phones) 2nd setting is TT= Touch Tone. I would guess that the setting should be set to TT on both cordless phones for touchtone.
Second thing to do is to plug in the base unit of your cordless phone to a jack that currently has a landline phone plugged into it that works and test again. If cordless phone works OK then go back to the original jack that didn't work and reverse the wires in the jack: that is what is known as a "polarity" issue.