The reliance on USB and computer support of an adapter for voip pstn combining. uses more energy than the : cost of the adapter than the amount you can save on your voip calling plan!
a usb port ad cpu use >420 watts.. fugre out that you pay $0.016 per KWH you pay over one e daollr per day in power more in commercial setting where peak power charges are incurred.
A review suggests how much power is used here.............
A non usb pstn voip pstn adapter is located here
View here and now.....
Thanks for viewing
Marc