I am trying to upgrade the processor in a DK280 base cabinet from a RCTUC/D to a RCTUE/F. Currently there is a RSIU attached to the ribbon cable connecting the other cards. I tried to do the upgrade and did not put the RSIU in and when I powered the system up I did not get a dial tone so I could not run the system initialization programs. My question is: is putting the RSIU in going to make a difference? After the card is in should I get a dial tone so I can complete the upgrade? Any help would be GREATLY appreciated !