Microsoft Lync Server picks up where Office Communicator left off and adds a number of useful organizational communication features. One key additoin is the survival branch appliance function, which makes sure that if two branches of the same organization are cut off in some way, the isolated nodes continue to function without a service interruption. A media bypass feature eliminates the need for mediation servers to convert codecs in order to send a voice communication. Lync server 2010 provides the ability to make all the roles virtual. A quality of service feature makes sure that video calls can't degrade the performance of voice calls, or that any volume of communication can't impact communications for the organization as a whole.