This document describes this IP phone error message and the necessary steps to troubleshoot it:
Error pass limit
Cisco recommends that you have knowledge of Cisco Communications Manager and Cisco IP Phones.
The information in this document is based on Cisco Unified Communications Manager 4.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.
Users are unable to make calls from an IP phone and receive the Error pass limit error message.
This issue can occur when the maximum number of calls on the line is reached or the user receives the Maximum Number of Calls and Busy Trigger on the line settings of the phone.
You can configure a maximum of 200 calls for a line on a device. The limiting factor is the total number of calls that are configured on the device. As you configure the number of calls for one line, the calls that are available for another line decrease. The default specifies four. If the phone does not allow multiple calls for each line, the default specifies two.
The busy trigger, which works in conjunction with Maximum Number of Calls and Call Forward Busy, determines the maximum number of calls to be presented at the line. If the maximum number of calls is set for 50, and the busy trigger is set to 40, then incoming call 41 is rejected with a busy cause (and is forwarded if Call Forward Busy is set). If this line is shared, all the lines must be busy before incoming calls are rejected.
Complete these steps in order to overcome this error message:
On the Cisco CallManager Admin page, choose Device > Phone > Maximum Number of Calls or Busy Trigger.
Reconfigure the IP phone that encountered this error message.
Increase the value of Maximum Number of Calls and Busy Trigger on the IP phone line configuration according to the number of shared lines (or the number of calls coming on the same line).
For example, you can set the busy trigger to 5 on a 7960 IP Phone since there are six lines. One line can be kept free for a conference or outbound call when all other lines are busy.
This issue can also happen due to Unassigned Directory Numbers (DNs). In order to resolve the issue, delete the unassigned DNs as explained in the CallManager 4.x: Delete Unassigned Directory Numbers Configuration Example document.