That's the only one that provides DC isolation so that it can be used without any additional hardware other than the music source. Other MOH line cards require a separate 403 card and mounting to keep each line card electrically isolated from the common music source. Otherwise, the parties on hold will be able to hear (and talk to) each other.

ITT made a K400-TPL card that did the same thing, but those will likely be even more difficult to find than the San Bar ones.


Ed Vaughn, MBSWWYPBX