The Cisco CP-PWR-CUBE-3 provides AC power to the Cisco 7900 series VoIP phones. Cisco does not bundle power supplies with their phones because they are often powered through the Ethernet cable via power over Ethernet. Those who do not have access to power over Ethernet will require a traditional external power supply to use the phone. The CP-PWR-CUBE-3 is the third generation of power supply from Cisco. It replaced the "CP-PWR-CUBE-2" and first generation "CP-PWR-CUBE" in 2005 as the standard power supply for all Cisco corded phones. The CP-PWR-CUBE-3 is a universal power supply and is compatible with virtually every phone Cisco makes except for the wireless versions (CP-792x) and some older conference phones (CP-7935/36). The first and second generations are not compatible with the newer versions of the 7900 series phones, therefore the CUBE-3 is recommended.• 100-240V - 0.6A 50-60Hz• 48V - 0.375A