Chapter 13. Implementing Telephony Call Restrictions and Control
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.)
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
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
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
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
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,
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.
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
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
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.
The default state of ALL devices in the CallManager cluster is the following:
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
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.
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.
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:
Figure 13-2. Partition Configuration Window
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
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:
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
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
panes. To reduce
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