Looking at the picture here: http://stepswitch.us/1A2-KTUs/KE-403A.htm (I don't have the practice) it appears to be an 18-pin card, and I suspect that you cannot just plug and play.
I believe, from memory, that you need to plug it into a specially-wired card slot that allows you to provide (at least) A battery, ground, music pair input, and 6 pairs output, one for each line that gets the MOH feature.

Maybe some other old phone guy who worked on ITT Kellog systems can shed some light.

Last edited by Arthur P. Bloom; 08/01/20 09:19 PM.

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