You do realise that it doesn't need to be streaming 48kHz 24 bit audio back up don't you? It could be something really low, like GSM which is 13.2 kbit/s. AMR

You do realise that it doesn't need to be streaming 48kHz 24 bit audio back up don't you? It could be something really low, like GSM which is 13.2 kbit/s. AMR is even lower! So to stream audio at the threshold where it is still legible, it doesn't need masses and masses of data as you presume.