Configuring Overlap Sending and Receiving with Cisco CallManager

Cisco CallManager version 3.2 and later
Catalyst 6500 with WS-X6608-E1 Card
Cisco 2600 and 3600 series routers running Cisco IOS® Software Release 12.2(2)XN

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.

Conventions

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

Background

Overlap signaling requires that called digits be sent one-by-one as they are received from the calling device. For Q.931, the first digit is sent in a call setup message and subsequent digits are sent in information messages. This technique is used when a receiving PBX must be able to recognize variable-length phone numbers, and requires that the sender signal the end of the call setup process. For Q.931, a “sending complete” message is used for this purpose.

The alternative to overlap signaling is enbloc signaling, which is the predominant dialing method in use today. When called numbers are sent enbloc, the digits are collected before being sent. For Q.931, digits are sent in a call setup message.

Configuring Overlap Receiving

Step-By-Step Instructions

To configure the Cisco CallManager server for overlap receiving, perform these steps:

Open the Cisco CallManager Administration page.
From the Service menu, choose Service Parameters.

The Service Parameters Configuration window appears. For more information, refer to Service Parameters Configuration.
Choose a server.
- When choosing the server from the drop-down list box, select your publisher server.
- When choosing the service from the left menu, select Cisco CallManager Service.
Change the value of the OverlapReceivingForPriFlag field (or the OverlapReceivingFlagforPRI field in CallManager 3.3(3) and later) to True.
Repeat Steps 3 and 4 for all subscriber servers.
Stop and start the Cisco CallManager service on all servers.

For more information, refer to Starting and Stopping Services.

Verifying the Configuration

To confirm that your configuration is working properly, collect the Cisco CallManager traces and open them with the Q.931 Translator. For more information, refer to Q.931 Translator.

This screen appears, showing this trace sequence:

Note: Certain show commands are supported by the Output Interpreter (registered customers only) , which allows you to view an analysis of show command output.