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 CoS applications in CUCM can be summarized as two distinctly separate implementations:
the traditional approach and the line-device approach. This section investigates the
difference between these two approaches and explains the advantages of using the linedevice
approach.
Figure 13-22 shows a simple single-site CoS deployment with four distinct classes of
service. Four partitions and four CSSs have been created. The route patterns for each call
type have been put into their respective partitions. The CSSs will be assigned to various
devices in the infrastructure. This is as simple as CoS gets.
Figure 13-22 Single Site with Four CoS Definitions
If the organization chooses to use the centralized call-processing model and an additional
site is added to the cluster, four more site-specific partitions will need to be created, and
four additional CSSs. In addition, the PSTN route patterns will need to be duplicated
and put into their site-specific partitions. The challenge in this scenario is that partitions and
CSSs need to provide two functions: 1) select the local PSTN gateway, and 2) control who
is allowed to dial what number.
Figure 13-23 illustrates a summary of the partitions, CSSs, and route patterns necessary to
achieve this solution. The solution includes four partitions per site: emergency partition,
local partition, national partition, and international partition. The number of required
V
IP
Local_css
LD_css
Intl_css
Internal_css
Calling Search
Spaces Partitions
Route
Lists
Route
Groups Devices
PSTN
Route
Patterns
Calling
Search
Space
Assigned
to Device
Based on
Class of
Service
All IP Phones
9.011!
9.011!#
9.[2-9]XXXXXX
[2-9]XX XXX
9.1[2-9]XX
911
9.911
Internal_pt
Local_pt
LD_pt
Intl_pt
PSTN
RG
PSTN
RL
328 Chapter 13: Calling Privileges
partitions is calculated by multiplying the number of required classes of service by the
number of sites. The example includes four classes of service per site. Implementations
may involve considerably more partitions and CSSs per site.
Figure 13-23 Centralized Call Processing with Four CoS Definitions
The traditional approach, outlined in the preceding section, can result in a large number
of partitions and CSSs when applied to large multisite deployments with centralized call
processing. This configuration is required because the device CSS is used to determine both
the path selection (which PSTN gateway to use for external calls) and the CoS.
It is possible to significantly decrease the total number of partitions and CSSs needed by
dividing the functions of site-specific routing and CoS between the line CSS and the device
CSS. The use of both a line- and a device-based CSS is called the line-device approach.
NOTE The traditional model of designing CoS in CUCM does not scale to large
deployments involving 25 or more sites.
V
V
V
V
Calling Search
Spaces Partitions Route Lists/Route Groups
OnCluster
IP Phones
Shared
Site1Emergency
Site1Local
Site1National 1RL 1RG
NRL NRG
Site1International
9.11
9.[2-9]XXXXXX
9.1 [2-9]XX [2-9]XX XXXX
9.911
9.011!
9.011!#
SiteNEmergency
SiteNLocal
SiteNNational
SiteNInternational
9.11
9.[2-9]XXXXXX
9.1 [2-9]XX [2-9]XX XXXX
9.911
9.011!
9.011!#
VM Ports, MeetMe...
Device Calling Search
Spaces (4 for Site 1)
Device Calling Search
Spaces (4 for Site N)
Site 1
Gateways
Site N
Gateways
Site1Internal
Site1Local
Site1National
Site1International
•••
•••
SiteNInternal
SiteNLocal
SiteNNational
SiteNInternational
Class of Service Approaches 329
In the line-device approach, CUCM performs a concatenation of both the line and device
CSSs for each IP phone. Follow these rules to implement the line-device approach:
■ Use the device CSS to provide site-specific call-routing information (which gateway to
select for PSTN calls). The device CSS will be an unrestricted CSS. This CSS is not
used to enforce CoS.
■ Use the line CSS to block the route patterns that are not allowed by CoS (independent
of the used PSTN gateway). This can be done effectively with translation patterns with
a block action that are put into partitions that only the line CSSs have access to.
■ To implement the line device CSS approach, a per-site unrestricted CSS will be configured.
This CSS will be applied at the phone configuration page to implement a
device-based CSS. Recall that every DN (line) inherits this CSS by default. This CSS
will contain a partition featuring route patterns that route the calls to the appropriate
local gateway per site.
■ Create CSSs containing partitions featuring blocked route patterns for those types of
calls not permitted by a user’s CoS, and assign them to the lines of the user’s phone.
If a user has access to all types of calls except international, that user’s line (or lines)
should be configured with a CSS whose first partition includes a route pattern that
blocks calls to 9.011!. Recall that CUCM will process the line CSS before the device
CSS. Even though the international call is permitted at the device level, the international
call is explicitly blocked at the line level CSS. As soon as CUCM matches on a
pattern in the line CSS, the call is routed or blocked. The user placing the blocked call
will hear a reorder tone or an annunciator message (if the annunciator media resource
is active). Figure 13-24 illustrates this procedure.
Figure 13-24 Line-Device CoS Approach
Line
Line CSS Line CSS
Selectively Blocks
Undesired Routes
(According to
Class of Service)
Device CSS
Allows Access to
All External Routes
Block Int’I Partition
9.011!
Resulting CSS
“Blocked”
Route/Translation Pattern
“Routed” Route Patterns
Block Int’I Partition
9.011!
Device CSS
PSTN Partition
9.[2-9]XXXXXX
9.1 [2-9]XX [2-9]XX XXXX
9.011!
PSTN Partition
9.011!
9.1 [2-9]XX [2-9]XX XXXX
9.011!
Device
IP
330 Chapter 13: Calling Privileges
Figure 13-25 illustrates the line-device approach with multiple sites. This approach results
in a significantly simpler configuration with many fewer partitions and CSSs.
Figure 13-25 Line-Device CoS with Multiple Sites
One partition is used per CoS that blocks those destinations that are not desired by the
appropriate CoS. These partitions are included in the device’s line CSS to always block
access to destinations that are not permitted for the corresponding CoS, regardless of the
PSTN gateway that is going to be used by devices of a certain location.
All possible PSTN route patterns are created once per PSTN gateway and put into a
partition that is included at the device CSS, thus allowing the local gateway to be used
for all PSTN calls that have not been blocked earlier by the line CSS.
Site1Devices
•••
•••
SiteNDevices
Calling Search
Spaces Partitions
Route
Lists
1RL
NRL
1RG
NRG
Route
Groups
OnCluster
IP Phones
Shared
VM Ports, MeetMe...
Site1PSTN
911
9.011!
9.011!#
9.911
9.[2-9]XXXXXX
9.1 [2-9]XX [2-9]XX XXXX
SiteNPSTN
911
9.011!
9.911
9.[2-9]XXXXXX
9.1 [2-9]XX [2-9]XX XXXX
9.011!#
Device CSS (1 for Site N) Device CSS (1 for Site 1)
V
V
Site 1
Gateways
Site N
Gateways
911 and Vanity Numbers 331
This approach has the significant advantage that only a single, site-specific partition (and
device CSS) is required for each site to allow local gateway selection, and only one partition
per CoS (independent of the site) is required to perform CoS enforcement.
Instead of requiring the number of partitions determined by multiplying classes of service
and sites, the number of partitions is determined by adding the required sites and classes of
service.
A deployment with four sites and four classes of service using the traditional approach
would result in 16 partitions, whereas the line-device approach results in only 8 required
partitions.