Sudden loss of full duplex on landline

[powlefa]

About a week ago, I noticed that there was no duplex on my landline calls. I would be speaking, and the person to whom I was speaking would start talking at the same time. I was not talking to fast-speaking New Yorkers who are schooled in the arts of interruption, so it was not a behavioral problem. I believe the problem is that my phone service has suddenly converted itself into a single duplex device--only one side of a conversation could be accommodated at a time.

  I can imagine the time-wasting potential of trying to deal with Verizon's repair service. Can anyone in this forum suggest a home-brew way to deal with my problem? (Of course, if it's something gone bad on Verizon's lines outside the house, I can't do anything.)

  This problem is completely unrelated to cell phone or broadband. My landline setup is totally separate from the others.

  Thanks.

--Fred Powledge