To consistently ensure the highest quality voice, you must follow industry best practices when implementing IP Telephony. Note that these suggestions are only options and might not fit individual business needs in all cases.

• QoS/CoS

  QoS for real-time packets is obtained only after a Class of Service (CoS) mechanism tags voice packets as having priority over data packets. Networks with periods of congestion can still provide excellent voice quality when using a QoS/CoS policy. The recommendation for switched networks is to use IEEE 802.1p/Q. The recommendation for routed networks is to use DiffServ Code Points (DSCP). The recommendation for mixed networks is to use both. You can also port priority to enhance DiffServ and IEEE 802.1p/Q. Even networks with sufficient bandwidth should implement CoS/QoS to protect voice communications from periods of unusual congestion that a computer virus might cause. For more information,

• Switched network

  A fully switched LAN network is a network that allows full duplex and full endpoint bandwidth for every endpoint that exists on that LAN. Although IP Telephony systems can work in a shared or hub-based LAN, a switched network provides consistently high results to IP Telephony.

• Network assessment

  A Basic Network Readiness Assessment Offer from Avaya is vital to a successful implementation of IP Telephony products and solutions. Go to the Avaya Support website at https://support.avaya.com for current documentation, product notices, knowledge articles related to the topic, or to open a service request.

• VLANs

  Placing voice packets on a separate VLAN or subnetwork from data packets is a generally accepted practice to reduce broadcast traffic and to reduce contention for the same bandwidth as voice. Note that Avaya IP Telephones provide excellent broadcast storm protection. Other benefits become available when using VLANs, but there can be a substantial cost with initial administration and maintenance.