Own a Pair of Clipper Chips
The AT&T TSD was an early 1990s telephone encryption device. It was digital. Voice quality was okay. And it was the device that contained the infamous Clipper Chip, the U.S. government’s first attempt to put a back door into everyone’s communications.
Marcus Ranum is selling a pair on eBay. He has the description wrong, though. The TSD-3600-E is the model with the Clipper Chip in it. The TSD-3600-F is the version with the insecure exportable algorithm.