Location Based Routing – Defined
Location Based Routing (‘LBR’), at its core, is the concept of ensuring long distance calls go in and out of the PSTN through a local carrier of a specific user that must adhere to regulations. In some countries, this a telecommunication regulation which makes sure tolls are not bypassed so long-distance revenue is maximized. The Location Based Routing feature from a Microsoft standpoint was first released with Lync Server 2013 and has now since been carried over to Microsoft Teams. If you have experience deploying LBR in the Lync Server and Skype for Business days, you will likely see similarities with Microsoft Teams as the same “logic”, we’ll call it, is used with Teams. That logic is nothing more than simply identifying users and SBCs locations via IP addressing and applying policies to such.
To learn more about LBR and calling scenarios that apply and don’t apply to LBR users, visit the following Microsoft docs site: https://docs.microsoft.com/en-us/microsoftteams/location-based-routing-plan
This article also assumes you understand Direct Routing . If not, please review that as well: https://docs.microsoft.com/en-us/microsoftteams/direct-routing-landing-page
Now, let’s get an understanding of LBR from the perspective of a few illustrations:
In the first illustration, we show that User 1 or User 2 is trying to call the US. You can see the signaling of the user tells Teams “Try and use the SBC in the United States to make a call to Chicago”. This would be against regulation as you tried to enter the PSTN local to Chicago, rather than out the local PSTN in New Dehli. This is considered “Toll Bypass”.
This second illustration shows the appropriate path, in which is signaling tells Teams “if you want to call the US, you need to go out your local gateway, through the PSTN then into Chicago”. This meets regulation and ensure tolls are going to be collected within India.
The third illustration simply shows how all calls should traverse the PSTN within the user’s respective locations. Essentially, each location needs its own PSTN Gateway/SBC connected to the PSTN.
So now that we understand LBR, logically, the next question is; How do we set it up?
Planning and Deployment
Out of the gates, It’s important to define the following requirements, which will then be configured within Teams in a table further down:
- The Region
- The Site within the Region
- Network Subnet at each site
- Trust external internet IP address for each site
- The PSTN Gateways/SBCs in each site
- *Any PBX’s that may be required to ensure Teams users can call PBX users, such as Cisco
- Users in each site
- PSTN Usage
- Voice Routes
- Voice Routing Policies
Now, let’s take a look at the fictitious scenario box detailing our setup in India, which is a heavily regulated country for LBR. The scenario box ensures traffic flows how we expect in illustration 3 shown above.
**Image is clickable to expand
Once those requirements are gathered, you can begin configuring the sites and users for LBR. Inside of the scenario box are associated commands that should be ran to setup LBR based on requirements. To summarize, here are the steps
- Gather all the requirements listed above
- Configure PSTN Usages
- Configure Online Voice Routing Policies for each site
- Enable LBR for each network site
- Enable LBR for each gateway/SBC
- Grant the CsOnlineVoiceRoutingPolicy to users that must have LBR applied
- Also, grant this to any user who roams to India or an LBR configured site
- Enable the AllowCallingPreventTollBypass flag within the Teams Calling Policy for LBR Users
- This also includes any roaming users
When users whom are enabled for LBR travel to sites enabled for LBR, the LBR enabled site takes precedents and forces calls through the local SBC
*If you have a required connection to a PBX for internal calling, you should have a separate Teams Registered FQDN/IP or separate SBC connecting to that PBX. In this scenario, you DO NOT apply LBR to that registered SBC. In the documented scenario above, NDPBX.contoso.com represents this SBC connecting to a Cisco System in New Dehli as illustrated below:
I hope this helps and add’s a little more clarity to your understanding of LBR.
Comments and edit requests welcomed
Jason Sloan – Cyclotron Group