The Cisco CP-PWR-CUBE-3 provides AC power to the Cisco 7900 series IP phone. The CP-PWR-CUBE-3 is identical to the CP-PWR-CUBE but is also compatible with all Cisco IP phones including the color screen IP phones (CP-797x) and the newly released CP-7961G and CP-7941G models.
The CP-PWR-CUBE-3 is the replacement for the CP-PWR-CUBE-2. When Cisco released its newer version of IP phones like the CP-7941G, CP-7961G and CP-7971G it began using this power supply. This power supply provides cleaner power to the phone and uses a longer plug to insert into the phone.