The base station may have gotten 'zapped' by a high voltage transient, they are not very well protected against transients arriving via the telephone line. Try removing the line from the base station to see if the display no longer gives you that 'line in use' message. If it does, the base station is toast. If it doesn't, dig around and find an non-electronic phone to plug into your phone jack to see if you have a dial tone. We keep at least one of the old style phones to use during power outages since cell phones are useless in our area.
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The base station may have gotten 'zapped' by a high voltage transient, they are not very well protected against transients arriving via the telephone line. Try removing the line from the base station to see if the display no longer gives you that 'line in use' message. If it does, the base station is toast. If it doesn't, dig around and find an non-electronic phone to plug into your phone jack to see if you have a dial tone. We keep at least one of the old style phones to use during power outages since cell phones are useless in our area.