We are discussing a 401A/B manual intercom card; a simple private talk path using button/buzzer signaling.
The discussion is that the 401 series of cards lacks any intelligence, as in deciphering tone or pulse dialing.
Yes, if you want to split hairs, you can use the CO Tip/Ring of the standard 400 card to provide access to an external product made by other manufacturers, but most do not require a 400-type line circuit in order to do this.
