CHAPTER
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Software Configuration Guide—Release 12.2(25)SG
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Configuring Voice Interfaces
This chapter describes how to configure voice interfaces for the Catalyst 4500 series switches.
This chapter includes the following major sections:
Overview of Voice Interfaces, page 28-1
Configuring a Port to Connect to a Cisco 7960 IP Phone, page 28-2
Configuring Voice Ports for Voice and Data Traffic, page 28-2
Overriding the CoS Priority of Incoming Frames, page 28-4
Configuring Power, page 28-4
Note For complete syntax and usage information for the switch commands used in this chapter, refer to the
Catalyst 4500 Series Switch Cisco IOS Command Reference and related publications at
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/index.htm.

Overview of Voice Interfaces

Catalyst 4500 series switches can connect to a Cisco 7960 IP phone and carry IP voice traffic. If
necessary, the switch can supply electrical power to the circuit connecting it to the Cisco 7960 IP phone.
Because the sound quality of an IP telephone call can deteriorate if the data is unevenly sent, the switch
uses quality of service (QoS) based on IEEE 802.1p class of service (CoS). QoS uses classification and
scheduling to transmit network traffic from the switch in a predictable manner. See Chapter27,
“Configuring Quality of Service,” for more information on QoS.
You can configure the Cisco7960 IP phone to forward traffic with an 802.1p priority. You can use the
CLI to configure a Catalyst 4500 series switch to honor or ignore a traffic priority assigned by a
Cisco 7960 IP phone.
The Cisco 7960 IP phone contains an integrated three-port 10/ 100 switch. The ports are dedicated
connections as described below:
Port 1 connects to the Catalyst 4500 series switch or other device that supports voice-over-IP.
Port 2 is an internal 10/100 interface that carries the phone traffic.
Port 3 connects to a PC or other device.
Figure 28-1 shows one way to configure a Cisco 7960 IP phone.