Survivable Remote Site Telephony

Class of Restriction Lists

In this blog, I will explain the Cisco IOS technique of applying class of service (CoS) restrictions. Previous blogs have covered calling search space (CSS) and partition configuration in Cisco Unified Communications Manager (CUCM) which will handle CoS call restrictions during normal operation of the network. Branch sites using Cisco Unified Communications Manager Express (CUCME) must rely on the Class or restriction list (CORLIST) functionality that is discussed in this blog. SRST will also need to rely on local CORLIST configuration when connectivity to CUCM from the branch location is down if call restrictions during an outage is a requirement. Protecting the organization against toll fraud during periods of network outage may seem like overkill, but CORLIST functionality may be mandated by a compliance standard.

This CORLIST blog series will explain the configuration of four different classes of service:

• Lobby CoS
• Intern CoS
• Employee CoS
• Manager CoS

Lobby phones will be able to dial the following PSTN destinations:
• Emergency 911

Interns will be able to dial the following PSTN destinations:
• Emergency 911
• Local PSTN calls

Employees will be able to dial the following:

• Emergency 911
• Local PSTN calls
• Long Distance PSTN calls

Managers will be able to dial the following:

• Emergency 911
• Local PSTN calls
• Long Distance PSTN calls
• International PSTN calls

The first step in creating CORLISTs is to define the members that will be used in each list. This is similar to the creation of partitions in CUCM. Every type of phone number will have a member defined in cor custom configuration mode as shown in the example below:

Dial-peer cor custom
name e911
name local
name longdistance
name international

The names defined in the cor custom configuration will be applied to incoming and outgoing corlists. An incoming corlist is like a keyring with one or more keys and an outgoing corlist is like a lock. The next step in the COR configuration is to define the outgoing corlists that will be applied to dial-peers in the branch gateway router. Corlists that will be applied in the outgoing direction can have multiple members, but is not necessary. It is best practice to configure outgoing corlists with only one member to simplify configuration and troubleshooting.

dial-peer cor list e911_PSTN
member e911
!
dial-peer cor list local_PSTN
member local
!
dial-peer cor list longdistance_PSTN
member longdistance
!
dial-peer cor list international_PSTN
member international

In the next blog, we will continue our discussion on the corlist CoS approach.

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