The Privatel 960V is a small (5.5″ x 3.5″ x 1.65″), portable (under a pound) telephone encryption device. It comes with a normal-looking power adapter such as might be used with any portable device — either U.S. or European (get both if you travel) — and a carrying case. The Privatel connects between the handset of your telephone and the body of the telephone, which allows it to be used on proprietary PBXs, ISDN terminals VoIP phones, and INMARSAT terminals, as well as standard analog telephones. Connecting it is easy: You unplug the coiled handset cord from your telephone and plug it into the side of the Privatel. You then take a short (provided) cable and connect the Privatel to the jack where you just unplugged the handset.
Original $595 each.
https://www.international-due-diligence.org/privateltm-960v-personal-telephone-security/