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.
Technical Tips Conventions for more information on document
Users are unable to make calls from an IP phone and receive the
Error pass limit
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
On the Cisco CallManager Admin page, choose Device >
Phone > Maximum Number of Calls or Busy Trigger.
Reconfigure the IP phone that encountered this error
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
4.x: Delete Unassigned Directory Numbers Configuration Example