Simplify new branch configurations using the Standard Local Route Group

Note: This isn’t a configuration guide to Standard Local Route Groups in your CUCM. This is really more of a document to help you understand how it works. If there is any interest, I may go back and create a document or video showing how to actually build this.

Section 1 – Normal Call Flow

Here is what CUCM call flows look like normally. I’m not going to dig into the nitty gritty, but this is the configurations that you have to set up whenever you set up a new branch office. Generally speaking, you will have 3-5 Calling search spaces. (Branch_A_Local_CSS, Branch_A_LD_CSS, Branch_A_Internal_CSS, Branch_A_International_CSS) Partitions for each CSS*. (Branch_A_LD_PT, Branch_A_Local_PT, Branch_A_Emergency_PT, Branch_A_International_PT)* Then each partition would contain anywhere from 1 to infinite amounts of Route Patterns. (911, @, 123XXXXXXX, XXXXXXX, 1[2-9]XX[2-9]XXXXXX, etc.) Then each route pattern must reference a route list, which contains route groups that were custom built for each call path needed (sip trunks for main calls and fxo cards for emergency calls if that is how your system is configured), then of course you always have to configure those call paths as well.

Figure 1.1 Normal Call Flow

[Branch A Phone] ──► [Branch_A_LD_CSS] ──► [Branch_A_LD_PT] ──► [Route Pattern] ──► [Branch_A_RL] ──► [Branch_A_RG] ──► [Gateway / SIP Trunk]

Section 2 – Understanding the Standard Local Route Group

Utilizing the Standard Local Route Group, we are able to bypass having to build calling search spaces, partitions, route patterns and route lists limiting the amount of configurations in CUCM that have to be built for each individual clinic. We can build one of each of these that references the Standard Local Route Group, and then reuse these over and over and only have to build a Device Pool and 911 Route Group for each branch office. And if you use CER or another e911 solution, you don’t even have to build the 911 route group for each branch office and can include that in your standard local route group.

Here is how the Standard Local Route Group Call Flow works.

Figure 2.1 Standard Local Route Group Call Flow

[Branch Phone (Device Pool)] ──► [Shared SLRG_CSS] ──► [Shared SLRG_PT] ──► [Route Pattern] ──► [RL_SLRG (Standard Local Route Group)] ──► [Device Pool's Assigned Local Route Group]

SLRG Example

Here is a real-life example of this working. In this example, all of our branch offices use a shared BRANCH prefix. We are assuming everything is already built and in the Device Pool; for the Standard Local Route Group, we have assigned the route group RG_BRANCH_SLRG_PSTN.

Figure 2.2 SLRG Example Call Flow

[Clinic Phone (DP_Clinic_A)] ──► [BRANCH_SLRG_LD_CSS] ──► [BRANCH_SLRG_LD_PT] ──► [1[2-9]XX[2-9]XXXXXX] ──► [RL_SLRG] ──► [RG_BRANCH_SLRG_PSTN (from DP_Clinic_A)]

Section 3 – Emergency calls utilizing Standard Local Route Group (SLRG)

If you do not currently utilize an e911 solution, and all emergency calls go out of the local gateway via FXO ports, you have to create an additional Local Route Group Name (e.g., lrg-emergency-1) under System > Device Pool > Local Route Group Settings for emergency calls that must also be defined in each Device Pool.

Section 4 – How to configure a new clinic for SLRG

When standing up a new branch office, after building the gateway(s), configuring the FXO ports, and all that fun jazz, configuring the SLRG is easier. We no longer have to build new route patterns, partitions, calling search spaces, and route lists. All we have to do is build a single route group that we will use for emergency calls, build a device pool and assign the standard local route groups, and then assign the phones the new device pool and the already built SLRG calling search space.

Step 4.1 – Build an emergency Route Group (RG_ClinicName_911)

Create a Route Group under Call Routing > Route/Hunt > Route Group pointing to the branch’s local voice gateway FXO port(s) for emergency 911 egress.

Step 4.2 – Build a new Device Pool

1. Name the Device Pool (e.g., DP_ClinicName).
2. Assign it the Default CUCM Group.
3. Select the branch PSTN route group (RG_BRANCH_SLRG_PSTN) for the Standard Local Route Group.
4. Select the branch 911 route group (RG_ClinicName_911) for lrg-emergency-1.

Step 4.3 – Assign configurations to clinic phones

1. Assign the new Device Pool (DP_ClinicName).
2. Assign the shared BRANCH_SLRG_XX_CSS Calling Search Space based on user requirements.
3. Configure phone lines based on standard telephone documentation.