first off, BFO means: Beat Frequency Oscillator and is a circuit which turns a dry sort of dit and dah of a morse code into a more hearable blip and bleep.
AS FAR as NO VOICE. What that means is, they can't transmit on that frequency things. Believe it or not, ADF at one time was an important tool to send out wx info, or other communications.
VORs could be used to transmit in response to aircraft radio transmissions.
Like: Oakland radio, cherokee 2346D listening on Woodside VOR, request sequence report for MRY.
I feel old