This document explains how to configure an external (PSTN/PBX) call
forward all (CFA) extension on the IP phone when performing overlap
There are no specific requirements for this document.
The information in this document is based on these software and
For more information on document conventions, refer to the
Technical Tips Conventions.
When your system is configured for overlap sending, you usually have a
route pattern configured with a digit followed by a period, such as "9.". With
this route pattern, if you want to configure an external CFA extension on the
IP phone, the Cisco CallManager only accepts the 9 and no additional digits. To
overcome this, you need to configure an additional route pattern with a
wildcard character, such as "9.!" and put this in a separate partition. Create
a calling search space (CSS). Put this partition as the highest priority in
this CSS. On the IP phone Directory Number configuration, put this CSS in the
Forward All field.
To configure the CFA extension, perform these steps.
Open the Cisco CallManager Administration window.
Create a partition.
From the menu bar, select Route Plan >
Click Add a New Partition.
Enter a name in the Partition Name field. In this example,
overlap is used.
Enter a description in the Description
Click Insert to add the new
Create a CSS. Select the created partition as the highest
In this example, overlap-css is
From the menu bar, select Route Plan > Calling Search
The Calling Search Space Configuration window
Click the Add a New Calling Search Space
Enter the appropriate information in the Description and
Available Partitions fields.
In the Selected Partitions field, select your newly-created
partition (in this case, overlap).
Use the up and down arrows to the right of the field to select
the newly-created partition.
Create an additional route pattern.
This should be similar to your existing route pattern along with
the wildcard character (!). For example, if the existing route pattern is "9.",
the new route pattern is "9.!".
From the menu bar, select Route Plan > Route
The Route Pattern Configuration window appears.
Click Add a New Route
In the Route Pattern field, type the route pattern digit along
with the wildcard character.
In the Partition field, assign the created partition (in this
case, overlap) to this route pattern.
Enter the remaining appropriate settings. Click
Go to the Directory Number configuration of the IP phone. Assign
the created CSS to Forward All.
This section provides the information to confirm that your
configuration works properly.
On the IP phone, click CFWdAll. Enter the external CFA
Note: Since you are using a route pattern such as "9.!", you need to wait
until the T302 timer expires before the Cisco CallManager accepts the CFA
extension. By default, this timer is ten seconds. If this delay is too long,
change the T302 service parameter to a shorter length of time, for example,
For more information on changing service parameters, refer to
There is currently no specific troubleshooting information available
for this configuration.