They do require a battery on 3&18 just like a manual intercom card.

Should be able to tie line side T&R from one to line side T&R on another and bingo-bango it should work. Go off hook on one and the other should ring. Not much to it, as I recall.

I always liked the ITT cards because they let you put a tie-line call on hold where the westerns didn't let you do that. Since it's a manually set up call anyway, even if you hung up, the other party would still be there so they wouldn't know if you put them on hold or just hung up, but I always liked the idea of a flashing lamp to remind you someone is on the other end of that thing. Also, the ITT cards are compatible with western's. I've wired them together and they play just fine together. Interesting that even with the combination, the user with the ITT card can use the hold key but the user with the western card can't.

I go off on little rants about this because I went back and forth with Arthur about this topic a while back. I said it was dumb that western didn't make provisions for using hold on a tie line circuit and since we all know what a western snob- ahem- aficionado- Arthur is, a colorful and lively discussion ensued.