Telephone Key Product Criteria

ENERGY STAR certified telephones --Voice over Internet Protocol (VOIP), Hybrid, and Analog1 --meet stringent energy efficiency requirements for power use.  Below we summarize the power use criteria for telephones – a complete description can be found in the ENERGY STAR specification (PDF, 173 KB). 

To become ENERGY STAR certified, a telephone’s partial on mode power2 (adjusted for an off mode incentive) must be below a maximum power level that is based on the phone type and features.



  • PP_ON  is the measured “partial on” mode power in watts (W)
  • POFF_INCENTIVE is the “off mode Incentive” (W)
  • PMAX is the “maximum average power” (W)

Off mode incentive is defined in the following manner (analog phones are not eligible for the incentive):



  • POFF is the measured Off Mode power (W). Off Mode is an optional state that saves power during periods of low use (such as at night). The phone is unable to make or receive calls while in Off Mode.

The maximum average power limit is calculated in the following manner:



  • PBASE is the base power allowance (W), for VOIP/Hybrid Phones:
    • 0.3 watts for additional handset
    • 2.0 watts for cordless, corded, or wireless
    • 2.5 for conference
  • PBASE is the base power allowance (W), for analog phones:
    • 0.3 watts for additional handset
    • 1.3 watts for cordless or conference
    • 1.1 for corded
  • PADDi is the power allowance (W) for each of the below features of the device:
    • 1.0 watt for Gigabit Ethernet
    • 0.2 watt for Energy Efficiency Ethernet 802.3az compliant Gigabit Ethernet
  • PPROXY is an additional proxy incentive(W) for the ability to maintain network presence while in a low power mode and intelligently wake when needed (analog phones cannot receive this incentive):
    • 0.3 watt for base capability
    • 0.5 watt for remote wake

1 Analog Telephone converts sound into analog waveforms for transmission through the Public Switched Telephone Network (PSTN).  Voice over Internet Protocol (VoIP) phones convert sound into

 Internet Protocol data packets for transmission through an Ethernet connection.  Hybrid Telephones do both.

2 “Partial on” mode may persist for an indefinite time when a Telephone is connected to a power source and a telephone line or other physical or wireless network connection and is capable of receiving a call. The Telephone is not receiving or transmitting sound, and the handset is “on the hook” and the speakerphone is not engaged.