I think the point here is telephony cable is telephony cable, and the reality is 4-pair network cable is telephony cable... The phones will work on CAT-3, CAT-5, CAT-6, 25-pair 1A2 station cabling, red/white paper pulp cable with lead casing, or whatever else they come up with provided the cable is physically sound, you just might need to do some creative connecting at the MDF.