Compare the system bandwidth requirements for a terrestrial $3-$kHz analog telephone voice channel with that of a digital one. For the digital channel, the voice is formatted as a PCM bit stream, where the sampling rate for the analog$-$to$-$digital $($A$/$D$)$ conversion is $8000$ samples$/$s and each voice sample is quantized to one of $256$ levels. The bit stream is then transmitted using a PCM waveform and received with zero ISI.