Both 75-ohm 4E1 adapter cable and 120-ohm 4E1 adapter cable are required for 4-portChannelized/4-port Fractional E1 FIC, but E1 cable is optional, so you need to order the E1 cable when purchasing an 4-port Channelized FIC or 4-port Fractional E1 FIC. Otherwise, it will not be provided.