QoS

Quality of Service (QoS) is a term covering several initiatives to maximize the voice quality heard at both ends of a call that originates or terminates on an IP-based telephone. These initiatives include various prioritization schemes to offer voice packets a larger or prioritized share of network resources. These schemes include standards such as:

• IEEE’s 802.1D and 802.1Q,
• the Internet Engineering Task Force’s (IETF’s) “Differentiated Services,”
• RTP Control Protocol (RTCP),
• Resource ReSerVation Protocol (RSVP), and
• port-based priority schemes such as UDP port selection.

Documentation for your LAN equipment details the extent to which your network can support any or all of these initiatives. See Server Administration, for some implications of QoS for the 4600 Series IP Telephones.

As of Release 1.7, the 4620, 4630, and 4630SW IP Telephones provided network audio quality information to the end user. This network audio quality information might be useful to the LAN Administrator. As of Release 1.8, all 4600 Series IP Telephones provide some level of detail about network audio quality. For specific information, see Network Audio Quality Display on 4600 Series IP Telephones.