Cisco Unified Communications Manager (CallManager)

Document ID: 45705

Contents

Introduction
Prerequisites
      Requirements
      Components Used
      Conventions
Multiple Calls Per Line
      Maximum Number of Calls
      Call Forward Busy Trigger
      CFNA Timer
Configure Multiple Calls Per Line in Cisco CallManager 4.0
Configure Multiple Calls Per Line in Cisco CallManager 4.1
Related Information

Introduction

This document explains how the multiple calls per line feature works in Cisco CallManager 4.x.

With Cisco CallManager releases before 4.x, a maximum of two calls were supported per directory number (DN). This document describes the feature in Cisco CallManager 4.x that expands the number of calls per DN, which makes it database configurable. The absolute maximum number of calls per line appearance is 200.

In earlier versions, only one device can have active calls for a shared-line appearance with multiple devices. In other words, if one device has an active call, no other devices can use this shared-line appearance to make a new call. Also, it cannot receive an incoming new call, or resume an on-hold call. The new feature in Cisco CallManager 4.x allows all devices with a shared-line appearance to be able to make or receive new calls or resume held calls at the same time.

Cisco CallManager 4.x introduces the Call Forward Busy Trigger concept to replace the original Call Waiting flag. The Forward feature for Call Forward Busy (CFB) is changed to allow a database configurable setting to trigger CFB on a per line appearance base. If all registered devices that share the same DN reject an incoming call, this call is forwarded to the CFB destination if it is set.

The Call Forward No Answer (CFNA) feature is changed to allow the database configurable setting for the alerting duration before CFNA is triggered, on a per DN basis.

Prerequisites

Requirements

Cisco recommends that you have knowledge of Cisco CallManager Administration.

Components Used

The information in this document is based on Cisco CallManager 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.

Conventions

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

Multiple Calls Per Line

These are the Multiple Calls Per Line enhancements in Cisco CallManager 4.x:

• Overcomes the limitation on the maximum number of calls per line.

• Introduces the CFB Trigger concept to replace the original Call Waiting flag.

• Configurable CFNA timer per line.

Maximum Number of Calls

In Cisco CallManager 3.x , the maximum number of calls allowed per DN is restricted to two. The new feature in Cisco CallManager 4.x makes this count database configurable, per line appearance, per cluster. However, due to the limited memory available in devices such as Cisco 7914 IP phones and the large number of lines that can be attached to them, it is necessary to limit the maximum number of calls for all lines on one single device. This limitation is stored in the database per device type.

• For Multiple Call Display (MCD) devices, the default maximum number of calls is set to 4 per line appearance.

• For non-MCD devices, this number remains at 2, due to the limited display capability. The default is set to 2 as well.

• The sum of the maximum number of calls for all line appearances per device should not exceed the limit for that device type. If it exceeds the limit, the device is no longer able to register.

Once this limit is reached, a user cannot use that line to initiate new calls and no new incoming calls are offered.

Note: An MCD device can display more than two call instances per DN at any given time. The display information for one call instance does not interrupt the display information for another call instance. Cisco IP Phones 7960 and 7940 are MCD capable, while 7910, SP12, and 30VIP are not.

See Table-1 for a comparison of the maximum number of calls in Cisco CallManager 3.x and Cisco CallManager 4.0.

Table-1

Call Forward Busy Trigger

Some users might wish to have incoming calls routed to a CFB destination earlier than reaching the maximum number of calls allowed per line appearance. The Busy Trigger feature is present in Cisco CallManager 4.0 to satisfy these user requirements. If all the devices that share a particular line are busy, the call to that specific DN is rejected with a busy cause. If the CFB destination is set for that DN, this rejected call is routed to the CFB destination.

The Busy Trigger is database configurable per line appearance and per cluster. It cannot exceed the maximum number of calls set for this DN. The default value for MCD devices is set to 2. By default, this busy trigger is 1 for non-MCD devices. As the maximum number of calls is already limited to 2, this cannot be set for more than 2.

See Table-2 for a comparison of CFB in Cisco CallManager 3.x and Cisco CallManager 4.0.

Table-2

CFNA Timer

In prior versions, the CFNA timer is configured through a service parameter and the default is 12 seconds. The new feature in Cisco CallManager 4.0 makes it database configurable, per DN, and per cluster. The default is 12 seconds. This applies to both MCD and non-MCD devices.

See Table-3 for a comparison of CFNA timer values in Cisco CallManager 3.x and Cisco CallManager 4.0.

Table-3

Configure Multiple Calls Per Line in Cisco CallManager 4.0

Complete these steps to configure multiple calls per line.

1. Enter the http://<Your CallManager 's name or IP address>/ccmadmin/ URL in the browser to connect to the Administration tool on your Cisco CallManager server.

2. Go to the Device menu and select Phone.

   

3. Click Find.

   The devices which are registered to this Cisco CallManager are listed. Click on a specific device in which you want to configure the features mentioned in this document.

   

4. Click on a specific line in the Phone Configuration Page.

   For example, click on Line 1 - 2000 on the left-hand side at the top.

   

5. You can find these options and configure them as required at the Directory Number Configuration page:

   • No Answer Ring Duration—This option allows you to configure the CFNA timer per DN, per cluster.

   • Maximum Number of Calls—This allows the maximum number of calls database configurable, per line appearance, per cluster rather than limit of two calls per DN as in the previous versions.

   • Busy Trigger—The minimum number of calls present in a specific line appearance that causes the device to reject new incoming calls with a busy cause for that line appearance. Only if all registered devices that share this line are busy, new incoming calls are rejected with a busy cause. This busy trigger is database configurable, per line appearance, per cluster. It cannot exceed the maximum number of calls set for this DN. The default for MCD devices is set to 2.

   

Configure Multiple Calls Per Line in Cisco CallManager 4.1

Complete these steps to configure multiple calls per line.

1. Enter the http://<Your CallManager 's name or IP address>/ccmadmin/ URL in the browser to connect to the Administration tool on your Cisco CallManager server.

2. Go to the Device menu and select Phone.

   

3. Click Find.

   The devices which are registered to this Cisco CallManager are listed. Click on a specific device in which you want to configure the features mentioned in this document.

   

4. Click on a specific line in the Phone Configuration Page.

   For example, click on Line 1 - 1005 on the left-hand side at the top.

   

5. You can find these options and configure them as required at the Directory Number Configuration page.

   • No Answer Ring Duration—This option allows you to configure the CFNA timer per DN, per cluster.

   • Maximum Number of Calls—This allows the maximum number of calls database configurable, per line appearance, per cluster rather than limit of two calls per DN as in the previous versions.

   • Busy Trigger—The minimum number of calls present in a specific line appearance that causes the device to reject new incoming calls with a busy cause for that line appearance. Only if all registered devices that share this line are busy, new incoming calls are rejected with a busy cause. This busy trigger is database configurable, per line appearance, per cluster. It cannot exceed the maximum number of calls set for this DN. The default for MCD devices is set to 2.

   

Related Information

• Cisco CallManager Administration Guide, Release 3.3(3)
• Cisco CallManager 3.3
• Cisco CallManager Software Support Page
• Voice Technology Support
• Voice and IP Communications Product Support
• Recommended Reading: Troubleshooting Cisco IP Telephony
• Technical Support & Documentation - Cisco Systems