CP 6921 Cisco 2-Line Office VoIP Phone support two lines, the user can have to service provider in the same phone at any given time, Cisco CP 6921 phone has a magnificent display owing to its large anti glare screen, cisco phone is a full duplex speaker phone hence one can put the phone in a speaker phone when two more people are using the phone. CP 6921 can be PoE powered as it is enabled.