Does the Cisco Unified Wireless IP Phone 7920 support Quality of Service (QoS)?
A. The Cisco Unified Wireless IP Phone 7920 support Layer 2 Enhanced Distributed Coordination Function (EDCF)-such as QoS for downstream (toward the access point) traffic. In addition, the Cisco Unified Wireless IP Phone 7920 dynamically announces its presence with the Cisco Aironet access point to ensure that its downstream traffic is placed into the High Priority queue on the access point. This dynamic announcement is done using Cisco Discovery Protocol . The Cisco Discovery Protocol packets are sent from the Cisco Unified Wireless IP Phone 7920 to the access point and identify the phone so that the access point can place all traffic to the phone in the High Priority queue. The Cisco Unified Wireless IP Phone 7920 marks Real Time Protocol (RTP) voice packets with DiffServ EF. The Cisco Unified Wireless IP Phone 7920 Skinny Client Control Protocol (SCCP) signaling messages are marked with DiffServ AF31 (Type of Service (ToS) 3). This matches the DiffServ markings of Cisco wired Ethern
