I am the inventor of patent 4131769. When I lost my home in 1990,my patent certificate was left behind. I didn't know my patent number until 2007, when I found my patent the Internet. I've been trying to find out what happened to my patent of a phone lock.
After describing my phone lock to a few people, I was told that their parent had a lock on their phone like the lock I described to them, thus I'd like to know who sold and who purchased patent #4131769.