Cisco Unified IP Phone 7900 Series

CallManager 4.x/5.x/6.x: ConfList Feature Fails with the "Error Unknown" Error Message on IP Phone Screen

Document ID: 110560

Updated: Jul 27, 2009



The Conference List (ConfList) feature of Cisco Unified Communications Manager fails with an error unknown error message. This document provides information on how to troubleshoot the issue.



Cisco recommends that you have knowledge of these topics:

  • Cisco IP Phone 7900 series

  • Cisco Unified CallManager 4.x

  • Cisco Unified Communications Manager (CallManager) 5.x/6.x

Components Used

The information in this document is based on these software and hardware versions:

  • Cisco IP Phone 7900 series

  • Cisco Unified CallManager 4.x

  • Cisco Unified Communications Manager (CallManager) 5.x/6.x

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.


Refer to Cisco Technical Tips Conventions for more information on document conventions.


In conference, when the user presses the ConfList button on an IP phone to get the participant list, an error unknown error message appears on the IP phone and the participant list is not displayed on the IP phone screen.

For example, the user has one phone in Europe and two phones in the United States, the Europe phone is in one cluster and the United States phones are in another cluster. The user calls from the Europe phone (454577) to a United States phone (8477886) then hits conference on the Europe phone and calls the other United States phone (8273958), then hits conference again. The conference is made with no problem. However, when the customer presses ConfList on the Europe phone, the user receives an Error Unknown error message.


This issue occurs due to incorrect User Locale settings on the Cisco Unified Communications Manager.

Perform these steps in order to resolve this issue:

  1. Install the required User Locale on your cluster when you want to make a conference call between geographically separated clusters.

  2. Ensure all the participants have set the same User Locale on all clusters.

    1. The user should set this Default User Locale parameter through the Enterprise Parameters Configuration page.

    2. Go to Device > Phone > Select the phone. The Phone Configuration window appears. Select the locale from the User Locale Parameter menu. Repeat this step for all the required phones in your cluster.

Related Information

Updated: Jul 27, 2009
Document ID: 110560