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Exbar security line cards
#488305 09/28/11 10:45 AM
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Has anyone ever worked with these line cards? I am assuming they were designed to scramble/descramble the conversation to provide a secure line...???

https://www.ebay.com/itm/Western-El..._DefaultDomain_0&hash=item2c5f93366b


Lou

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Re: Exbar security line cards
#488306 09/28/11 01:43 PM
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click, and go to page 39

No. They do not perform scrambling/descrambling.

In 1A2 systems, on standard 400-type line cards, STA T&R (and the internal circuitry of the telset, such as the network, transmitter and receiver) can be accessed at the CO T&R terminals of the card, if a phone is on-hook, and a line key is depressed.

When a line is idle, or placed on Hold, (and the user has an expectation of privacy) a listening device could be attached to the CO T&R, allowing eavesdropping of the office to occur via the STA T&R leads.

These cards, like the SanBar 4001A & B versions and several others, have a wiring option / feature that prevents the CO T&R from reaching the telephone set when the line is idle or on Hold, preventing electronic eavesdropping.

Interestingly, the SanBar company made them, and then they went out of business. The name "Exbar" suggests that former employees may have taken the design and formed a new company to supply these cards to the TSG. (Just a wild guess, of course, but if I had done that, I probably would have used that name, too.)


Arthur P. Bloom
"30 years of faithful service...15 years on hold"

Re: Exbar security line cards
#488307 09/28/11 07:31 PM
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What Arthur said.

At the time of manufacture, sanbar (and then exbar) cards were ONLY available for purchase by the Government. We had a request for them from a customer and could not purchase them for love or money.

Sam


"Where are we going and why are we in this hand basket?"
Re: Exbar security line cards
#488308 09/29/11 07:26 AM
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Thanks for the information. Pretty interesting about the San/Bar / Exbar relationship. I think that San/Bar was located in Irvine, CA as well so it would make sense that they were related.

Lou

Re: Exbar security line cards
#488309 09/29/11 07:28 PM
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I was wondering if this security concern about evesdropping was the reason that the last version of Western Electric key telephone sets were made with the lineswitch that broke both the tip and ring?These sets had the letter S added to their model#.{2565HKMS,for example]


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