S23 ultra live demo unit - no sim?

I found an offer to buy s23 ultra for about 100$... However it is a live demo unit with no IMEI... The owner is selling bunch of different models of samsung phones, all demo units... the seller says if you put SIM card in it doesn't work. Can't make calls/texts... but he said that there might be a work around for this... is it true? Can it be transformed into a fully functional device?