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Chapter 13. Implementing Telephony Call Restrictions and Control

This chapter covers the following topics:

Defining Class of Service as it relates to users of a phone system
Defining partitions and calling search spaces and identifying the components of each
Configuring partitions and calling search spaces in Cisco CallManager to assign calling privileges to users and devices
Defining time-of-day routing and identifying its uses and components
Configuring time-of-day routing to control call routing based on the time of day, day of week, and day of year when the call was made

An important dial plan consideration is the assignment and enforcement of calling privileges. You might want company executives to have different calling privileges than receptionists, or employee phones to have different calling privileges than lobby phones. You might also want to place further restrictions on the times that these privileges are available, for example, by allowing international calls to be placed only during business hours to prevent unauthorized use after hours. Partitions, calling search spaces, and time-of-day routing are the primary class of control components that enable you to assign and enforce calling privileges.

This chapter discusses how to deploy calling restrictions and control by using Cisco CallManager partitions, calling search spaces, and time-of-day routing.

Class of Service Overview

Class of Service (CoS) is a collection of calling permissions and restrictions that you assign to individual users or groups of users. (The terms calling permissions and calling restrictions are used interchangeably in this chapter.)

Note

CoS as it applies to telephony networks holds a completely different meaning than its application in quality of service (QoS). CoS in telephony means the implementation of calling restrictions, whereas CoS in data networking means the application of a data link layer marking in a data frame.

Examples of class-of-service permissions are as follows :

One class of users can place toll calls during normal business hours, but not at other times.
Lobby phone users can dial the local emergency numbers and campus extensions, but cannot dial local, long-distance, or international numbers .
Receptionists can dial anywhere within the company and all local area codes, but cannot dial long-distance or international numbers.
Executives can call anywhere except 900 area codes.

Cisco CallManager uses partitions, calling search spaces, and time-of-day routing to implement class-of-service restrictions.

Partitions and Calling Search Spaces Overview

A partition is a group of directory numbers (DNs) with similar accessibility. A calling search space defines which partitions are accessible to a particular device. A device can call only the DNs located in the partitions that are part of its calling search space.

A partition comprises a logical grouping of directory numbers (DNs) and route patterns with similar reachability characteristics. Items that are placed in partitions include DNs and route patterns (or anything else that has a directory number). For simplicity, partition names usually reflect their characteristics, such as "NYLongDistancePT," "NY911PT," and so on.

A calling search space is an ordered list of partitions that Cisco CallManager digit analysis looks at before a telephone call is placed. Calling search spaces then determine the partitions that calling devices, such as Cisco IP Phones, Cisco IP SoftPhones, and gateways, can reach when attempting to complete a call. If a device attempts to reach a route pattern or DN that is not contained in one of the partitions in its calling search space, it receives a fast busy signal (or a prerecorded message played by the annunciator service).

Items that can be placed in partitions all have a dialable pattern, which includes phone lines, route patterns, translation patterns, computer telephony integration (CTI) route group lines, CTI port lines, voice-mail ports, and Meet-Me conference numbers. In short, you can place absolutely anything that has a directory number into a partition. To do this, you group common numbers together. For example, you could create an internal number partition (perhaps named INTERNAL_PT) that contains all numbers internal to the organization, an emergency partition (named EMERGENCY_PT) that contains route patterns representing emergency numbers such as 911, and a local PSTN partition (named LOCAL_PT) that contains route patterns representing local PSTN numbers. By doing this, you have grouped the numbers to assign the calling restrictions. By default, everything belongs to the <NONE> partition (or no partition assignment), which is why there are no calling restrictions.

Conversely, you can assign a calling search space to all devices capable of dialing a call, such as telephones, telephone lines, gateways, and applications (via their CTI route groups or voice-mail ports). The calling search space contains nothing more than an ordered list of partitions. When you assign a calling search space to a device, that device can reach whatever is in the partitions listed in the calling search space. For example, you could create a calling search space named INT_EMG_CSS that contains just the internal and emergency partitions (INTERNAL_PT and EMERGENCY_PT mentioned in the previous paragraph). By assigning this to an IP Phone, you will have restricted it to only dialing internal extensions and emergency numbers.

Note

Regardless of the calling search space assigned, all devices are able to reach any number assigned to the <NONE> partition. Because of this, Cisco recommends that you should never leave numbers assigned to the <NONE> partition.

As shown in Figure 13-1, the DNs of lobby phones and break room phones are placed into partition A. Partitions B, C, D, E, and F contain the route patterns to reach local numbers, long-distance numbers, international numbers, and company extensions.

Figure 13-1. Partition and Calling Search Space Example

The calling search space for the lobby phones includes only the partitions containing the company extensions and the local emergency numbers. Therefore, a lobby phone located in partition A has a calling search space containing partition A, E, and F and can dial only company destinations, including the break room (in other words, devices belonging to the same partition) and local emergency numbers (for example, 911 in the United States).

Note

In addition to assigning calling search spaces to the phone or directory number, you can assign calling search spaces to the call forwarding fields of an IP Phone (call forward busy, call forward no answer, and so on). This allows you to place different calling restrictions beyond normal calling when a user forwards their phone.

Calling Search Spaces Applied to Gateways and Intercluster Trunks

In addition to applying calling search spaces to the IP Phones in the network, you must also apply them to the gateways and intercluster trunks. By default, the gateways and intercluster trunks of the network are assigned a calling search space of <NONE>. This calling search space can only access the directory numbers and route patterns assigned to the <NONE> partition.

Tip

The default state of ALL devices in the CallManager cluster is the following:

Partition: <NONE>

Calling Search Space: <NONE>

Even though it might appear as though these mean "no assignment," there is an unconfigurable partition and calling search space called <NONE>. The <NONE> calling search space only has access to the devices in the <NONE> partition. As you begin to assign directory numbers and route patterns to partitions other than <NONE>, any devices with the <NONE> calling search space (default) will lose access to the reassigned numbers.

The previously mentioned tip warrants special consideration when dealing with gateways and intercluster trunks. Because these devices are assigned the default calling search space of <NONE>, they will begin to lose access to the cluster directory numbers as you assign them to other partitions. The directory numbers that the gateways and intercluster trunks have access to affect inbound calls to the cluster.

For example, you could create a calling search space named INT_LOC_CSS that only allowed access to directory numbers assigned to the Internal (INTERNAL_PT) and Local PSTN (LOCAL_PT) partitions. If this INT_LOCAL_CSS calling search space were applied to an Intercluster Trunk to a remote CallManager cluster, any calls coming inbound from the remote cluster would only be able to reach the internal and local PSTN extensions. This feature is useful when you do not have administrative control of the remote cluster but have the need to configure call restrictions into your cluster from the remote devices.

Note

This feature works identically for gateway devices configured in the CallManager cluster. The calling search space applied to gateway devices affect calls coming inbound (into the cluster) from the gateway. It does not affect calls outbound to the gateway from the devices in the cluster.

Partition Configuration

To configure partitions, choose Route Plan > Class of Control > Partition . When the Find and List Partition window appears, click the Add a New Partition link. The Partition Configuration window that is shown in Figure 13-2 appears. From here, you can add a maximum of 75 partitions at a time using the following syntax:

<partitionName> , <description>

Figure 13-2. Partition Configuration Window

Note

Class of Control is a new submenu item under the Route Plan menu in Release 4.1 of Cisco CallManager. The Class of Control submenu includes partitions, calling search spaces, and time-of-day routing items.

Cisco CallManager Administration requires that you enter the partition name . However, adding a description for the partition can be useful for documentation purposes.

Using partitions allows you to group DNs with similar characteristics together. For example, the network administrator at ABC Company must allow certain individuals to call the DNs in the 1 xxx and 2 xxx ranges. Before assigning the DNs to a partition, the administrator must first configure the partitions using the Partition Configuration window in Cisco CallManager Administration. The administrator could add the necessary partitions using the following format:

DN_1XXX, Directory Numbers 1000-1999
DN_2XXX, Directory Numbers 2000-2999

After the administrator adds the partitions, DNs must be assigned. To do this, the administrator must enter the configuration mode of the telephones or route patterns that have the DNs, proceed to the Directory Number Configuration window, and choose the newly created partition from the menu, as shown in Figure 13-3.

Figure 13-3. Assigning a Directory Number to a Partition

Calling Search Space Configuration

After configuring the partitions, you can configure the calling search spaces that contain a prioritized list of the available partitions. Figure 13-4 shows the Calling Search Space Configuration window in Cisco CallManager Administration (choose Route Plan > Class of Control > Calling Search Space ).

Figure 13-4. Calling Search Space Configuration Window

You can use the arrows between the Available Partitions and Selected Partitions panes to choose the partitions that you want to add to the calling search space. You can reorder partitions by using the arrows to the right of the Selected Partitions panes. To reduce call-processing time, place the partitions with the most frequently used numbers at the top of the Selected Partitions list with the exception of critical partitions. Emergency number partitions or partitions containing blocked numbers are usually placed near the top of the list.

The calling search space gives you the ability to place any number of calling restrictions on the IP telephony network. For example, to restrict access to the 1XXX and 2XXX partitions, the network administrator from the ABC Company must create a calling search space that is named "1XXX_Only_CSS" and add the DN_1XXX partition to this calling search space. The administrator then creates another calling search space named "2XXX_Only_CSS" and adds the DN_2XXX partition to this calling search space. Finally, the administrator creates a calling search space named "All_DNs_CSS" and adds both the DN_1XXX and DN_2XXX partitions to this calling search space.

After configuring the calling search spaces, the administrator assigns them to the various network devices. For example, telephone A is assigned the 1XXX_Only_CSS calling search space, which means that telephone A can call only the DNs that are assigned to the partition DN_1XXX. By assigning telephone B to the 2XXX_Only_CSS calling search space, the administrator restricts telephone B from calling any numbers outside of the DN_2XXX partition. If the administrator assigns telephone C to the All_DNs_CSS calling search space, telephone C can call the DNs that are assigned to both partitions DN_1XXX and DN_2XXX.