Did all US DC's ship with a 56K modem as standard?

I have a DC that has a "blank" modem, another words that instead of the modem being snapped in place there is a piece that fits the same spot the modem is in and looks exactly like a the modem but has no internals nor a plug-in for a phone line. I was thinking maybe this DC was a kiosk model and it was sent that way on purpose as not to sold to the public.
Anyone else come across one like this?