Cisco Unified Contact Center Express

Why Is the Voice Playback Slow and Distorted?

Document ID: 45382

Updated: Feb 02, 2006



Voice monitoring and recording are features of the IP Integrated Contact Distribution (ICD) Cisco Supervisor Desktop client. These features allow a supervisor to silently monitor and record the phone call of an agent. This document describes the reason that monitoring and recording of IP calls on two different Cisco Catalyst 6509 switches fails with distorted voice in a Cisco IP Contact Center (IPCC) environment.



Readers of this document should be knowledgeable of the following:

  • Cisco CallManager

  • Cisco IPCC Express

  • Cisco Catalyst 6509 configuration

Components Used

The information in this document is based on the software versions:

  • All Cisco CallManager versions

  • All Cisco IPCC Express versions

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.


For more information on document conventions, refer to the Cisco Technical Tips Conventions.

Background Information

When the monitoring and recording failure occurs, the topology is set up, as shown in Figure 1.

Figure 1: Topology



When performing voice monitoring and recording between two agents on the same Catalyst 6509 switch, the voice playback is normal. However, when performing voice monitoring and recording between two agents on different Catalyst 6509 switches, the voice playback is slow and slightly distorted.


This problem is a Catalyst 6509 Remote Switched Port Analyzer (RSPAN) configuration issue. When configuring RSPAN, the original RSPAN setup is VLAN RSPAN. Since trunk port is part of the VLAN, it also monitors and records all traffic over the trunking port. This creates a packet duplication problem in the process of voice monitoring and recording.

To fix the duplicate-packet problem, change the RSPAN configuration from VLAN RSPAN to port RSPAN. Ports for CallManager, IPCC Express servers and agents (except trunking ports) should be configured with port SPAN. When configuring the port, configure either transit (Tx) or receive (Rx), but not both.

Related Information

Updated: Feb 02, 2006
Document ID: 45382