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New Member

CUCM Partitions & CSS Best Practices


i was thinking about Cisco suggested partition and CSS best practices that i want to summarize:

1.   Create a Partition with all Blocked numbers (eg: Blocked_PT)

2.   Create a Partition with all Allowed numbers  (eg: Allowed_PT)

3.   Create a CSS with the Blocked_PT partition first and the Allowed_PT after.

This is also useful for centralized multisite enviroment because the Blocked_PT is the same for all sites, while we must only create 1 Allowed_PT for each site (because it's linked to the site gateway or Route List).

That is ok, but now i need to do some considerations and questions about real life examples: the procedure i wrote is good for sites that have 1 CSS and all users with same calling privileges, but must be different for multi-CSS CUCM systems.

I want to submit an easy example:

1.   I have 3 type of users with 3 calling privileges: local, long distance, mobile

2.   Create 3 partitions: local_PT, long_distance_PT, mobile_PT.

3.   Create 1 partition (allowed_PT)

4    Create 3 Route Patterns: 1st linked to local_PT, 2nd linked to long_distance_PT , 3rd linked to mobile_PT. All these patterns are blocked.

5.   Create a Route Pattern that contains all dialable numbers (eg: 0.!) linked to allowed_PT. I route this pattern.

So, since i have different user privileges i need 3 CSS made like this: (tell me if my route plan is correct)

                      Local_CSS                                           Long_distance_CSS                                Mobile_CSS                  


                  long_distance_PT                                            mobile_PT                                         allowed_PT              

                       mobile_PT                                                  allowed_PT   


Explainig these CSS is simple: for example Local_CSS have partitions in an order that block long_distance and mobile numbers allowing only local calls. So Cisco best practices must be modified because i need more than 1 partition blocking. My considerations and questions are:

A. i must think about EVERY dialable blocked number (eg: service, call center, toll, etc...) and create a partition linked to a Route pattern

B. For low privileged users, i will have a CSS with a long list of blocked partitions: can be this too much processor intensive ? Or can be a configuration problem ? The CUCM must examine a long list of blocked patterns before allowing the call...

Thank you,


VIP Super Bronze

Re: CUCM Partitions & CSS Best Practices

The way you are explaining it sounds like the best practice from CCM 4.1 and is no longer current. The SRND for UCM has been updated multiple times since then. The more modern design is summarized as all dialing restrictions are placed on the LINE CSS while all route-related patterns/partitions are placed on the DEVICE CSS. I won't go into all the design implications to that since it takes the SRND roughly 100 pages to document everything out.

Essentially you will create a CSS per restriction level (local, long distance, etc) and apply that to the directory number. You will also create a CSS with one or more partitions and include the necessary route patterns. This will be applied to the device. Until UCM 7 this typically resulted in a new device-level CSS per site; however, the Local Route Group can negate this in some designs. The LRG allows you to add a route group to the device pool and instruct route patterns/route lists to use the routes included in whatever the user's LRG is.

Read the dial plan chapter of the SRND. It's long but walks you through all of this.

New Member

Re: CUCM Partitions & CSS Best Practices

Hi Jonathan,

thank you for reply. I will use the line/device approach putting a CSS that permits all destinations on devices and another CSS that blocks desidered patterns on the line. I have another question: with this method i can reduce the number of partitions. If i have, for example, a network with 1 main site and 100 remote sites i need:

- 1 partition for all internal IP phones

- 100 partitions (1 for each site). Then i associate them with the Route Patterns containing the Gateway/route list specific for each site.

- N partitions for Class of Services

My question is: can i use the "Standard Local Group" feature to reduce the 100 site partitions to 1 (using 1 Device pool for each site containing the reference to the local Voice Gateway) ?

Thank you,


VIP Super Bronze

Re: CUCM Partitions & CSS Best Practices

Yes; that is what the Local Route Group was intended to address.

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