to coupler 88 via low pass filter 86 which filter serves to protect the public telephone network from injection of rf energy because limits on rf injection into the public telephone network are considerably more severe below 6 mhz filter 86 may not be required if shifted video and control signals imposed on continued subscriber line 62 are confined to frequencies higher than 6 mhz coupler 88 serves to combine incident video signals from shifter 78 and incoming voice signals from subscriber phone line 60 and transmit the combined signal along continued subscriber phone line 62 coupler 88 also relays audio or voice signals and control signals transmitted from a subscriber termination of line 62 control signals are advantageously transmitted from a subscriber terminal of line 62 encoded in a frequency band centered on 10 7 mhz as described in the prior art control signals are relayed from coupler 88 to a command interpreter 84 which decodes the incoming control signals and issues a command to tuner 76 for determining channel selection and optionally issues an instruction to shifter 78 to determine frequency band selection audio band signals incident on couple 88 from a subscriber end of line 62 are transmitted via low pass filter 86 to subscriber phone line 60 whereupon these audio band signals are accepted and processed in the normal way by the local area public phone network terminal unit u 2 is represented in greater detail in fig3 as discussed above with reference to fig1 unit u 2 is provided with input 66 and outputs 68 and 70 input 66 connects via a twisted pair not separately.