Geez, it figures that you would have caught that! Yes, even the 400H had a reed relay to detect incoming ring current on the line. Man, I can't pass much of anything past you, Bruce!

I agree that the 400G was by far the most stable and reliable line card. There were too many revisions of the 400D and for some reason, our site situations always required a different revision. Sort of like Partner systems. Whatever you needed, you didn't have the correct revision.

I think that the only reason that the 400G went away was because dedicated phone equipment closets started to go away in the early 1980's. At that time, equipment had to start being installed with in the office space. The clicking of relays might have been objectionable, resulting in complaints. The 400H was virtually silent in operation.

Hey, I am just guessing.

Ed Vaughn, MBSWWYPBX