Line-powered VoIP

One of the energy implications of Voice over IP (VoIP) telephony has been that the phone handset needs its own DC power source, typically a plug-in power supply (as opposed to a POTS handset, which receives power over the phone line from the phone company's central office). PoE allows the DC power to be distributed over the ethernet wire, which moves the power supply from the handset to the ethernet switch (in a home setting, this might be the broadband router). Now, Covad is introducing line-powered VoIP, in which the DC power is again distributed from the central office:

"This system of service delivery means that line-powered voice access provides a full primary telephone line replacement service. Most importantly, it is powered at the central office, just like traditional local service, ensuring continued phone service during a power outage. Also, it allows customers to use their existing phones and inside wiring, and avoid time-consuming and costly installations."

It's hard to know what effect this will eventually have on energy use (since it's replacing one type of central office power supply with another), but it seems preferable to having a separate power supply for each handset. Does anyone know how the power use of VOIP handsets compares to their POTS counterparts? I suppose cordless phones will still need a separate power supply for battery charging, so maybe it won't change today's situation very much (i.e., power supplies at both ends of the wire).

(from Yahoo Finance)