Network sites and Location-Based Routing
Teams decides how to treat calls and meetings by knowing where a user is on the network. If you plan sites and subnets well, location-based features work without extra effort.
Network topology
In the Teams admin center, Locations > Network topology holds the building blocks:
- Network regions: a large geographic area, used with media routing.
- Network sites: one office or branch, belonging to a region.
- Subnets: IPv4 or IPv6 ranges mapped to a site. Teams matches the client’s IP to a subnet to find the site.
A user outside every defined subnet is treated as being at an unknown location. The same site data feeds emergency locations, network roaming and call quality reports.
For policy to follow the site, the meeting policy setting Network configuration lookup must be On. Without it, the client does not look up its site.
Location-Based Routing (LBR)
LBR controls toll bypass. It limits which PSTN gateways a user may use, based on where the user is. It works with Direct Routing only, not Calling Plans.
To set it up:
- Define sites and subnets.
- Enable LBR on the site that holds the gateway (
Set-CsTenantNetworkSite -EnableLocationBasedRouting $true). - Link each SBC to a site (
Set-CsOnlinePstnGateway -GatewaySiteId ... -GatewaySiteLbrEnabled $true). - Enable LBR for the users in their voice routing or calling policy.
An LBR-enabled user can call the PSTN through an SBC only when both are at the same site. Calls that would bypass the toll are blocked.
Local Media Optimization (LMO)
LMO keeps media local. Signaling still goes through the central SBC, but the audio flows between the user and the nearest SBC. It reduces WAN bandwidth and delay. LBR is about permission, LMO is about the path.
Which to choose
| Requirement | Use |
|---|---|
| Block toll bypass by location | Location-Based Routing |
| Keep media inside the branch | Local Media Optimization |
| PSTN survives internet outage | Survivable Branch Appliance |
| Roaming settings by office | Network sites + Network configuration lookup |
Exam traps
- LBR does not work with Calling Plans or Operator Connect.
- A voice routing policy chooses a route; it does not restrict by user location.
- Adding subnets in Call Quality Dashboard does not change Teams admin center sites.
- LBR and LMO are different. Do not swap them.
Practice questions
Choose an answer, then review the explanation to check your understanding.
1. Users in the Mumbai office must be able to use SBC1 for PSTN calls only while they are physically in that office. What should you use?
Show answer
Answer: B.Location-Based Routing ties the gateway to a network site (Set-CsOnlinePstnGateway with GatewaySiteId and GatewaySiteLbrEnabled), so the SBC is used only from that site.
2. A branch must keep PSTN media local instead of sending it to the central SBC. Which feature is designed for this?
Show answer
Answer: A.Local Media Optimization lets media take the shortest path between the user and a local SBC, while signaling still goes through the central SBC.
3. A company adds new sites and wants location-based Teams reports and network roaming to work for them. What must be defined in the Teams admin center?
Show answer
Answer: B.Sites and subnets under Locations > Network topology are the source for location features such as roaming, emergency location and LBR.
4. For network roaming policy settings to apply when a user joins a meeting from an office, which meeting policy setting must be on?
Show answer
Answer: B.Network configuration lookup makes the client look up its network site, so the site-specific settings are used.