Home phone wattage. What is the Max Consumption for Polycom VVX and VVX? - VoIP Insider -, Home phone wattage. A cordless phone will typically use between 2 and 3 watts of power per an hour both during active usage and when recharging. A cordless phone is typically left plugged in 24 hours a day, not much can be done to reduce the power consumption of your cordless home phone except limiting the number of phones you have.