Local Media Optimization for Direct Routing

Publisher

Microsoft

URL

https://learn.microsoft.com/en-us/microsoftteams/direct-routing-media-optimization

Published

2026-09-10

Updated

unknown

Accessed

2026-09-30

HTTP status

200

License

Microsoft Learn terms of use; no-redistribution; short excerpts and locators only

Source notes citing this source

• Plain media bypass cannot serve branch SBCs that lack public IPs, because bypass requires the client to reach the SBC's public IP while downstream SBCs are reachable by Teams only through a proxy SBC defined in the LMO virtual topology; a proxy/downstream design therefore implies Local Media Optimization. inferred in context
• In a proxy/downstream LMO design the proxy SBC must have IP reachability to each downstream SBC's internal address, since external users' media and Only-for-local-users cross-site media are relayed by the proxy to the downstream SBC. inferred in context
• Microsoft recommends Local Media Optimization for keeping media inside the intranet, but says a tenant that already uses media bypass with only the public IPs of its SBCs does not need to move to Local Media Optimization. in context
• In the central-SBC scenario the SBC offers its internal IP for media when the user is on the corporate network and its external (public) IP when the user is outside it, while being visible to Teams Phone through its external IP only. in context
• Downstream SBCs have no public IPs but can be assigned to voice routes; users in the downstream SBC's branch send media to it directly, while external users send media to the proxy SBC's public IP, which proxies it to the downstream SBC. in context
• After a Teams user puts an LMO call on hold and resumes it, the call continues via the central (proxy) SBC rather than the optimized path, because hold escalates the call to multiparty and it is by design never de-escalated. in context
• In Always bypass mode an internal user's media goes to the downstream SBC's internal IP wherever in the corporate network the user is, and Microsoft recommends this mode when connectivity between branch offices is good. in context
• In Only for local users mode media goes directly to the downstream SBC's internal IP only for internal users in the same branch; Microsoft recommends it when links between branches are poor but each branch links well to a regional office, with the regional proxy SBC set to Always and downstream SBCs set to OnlyForLocalUsers. in context
• With Local Media Optimization, internal users must have media connectivity to the SBC's internal IP; there is no fallback to public Transport Relays because the SBC offers an internal IP. in context
• Local Media Optimization lets administrators keep media local within corporate network subnets and allows media between Teams clients and SBCs even when the SBCs sit behind corporate firewalls with private IPs not directly visible to Microsoft. in context
• Microsoft's LMO examples use an Online Voice Routing Policy whose priority-1 route sends local numbers (for example ^+84(\d{9})$) to the downstream SBC and whose priority-2 route .* sends all other calls, and local calls if the downstream SBC fails, to the proxy SBC. in context
• Local Media Optimization supports two scenarios: a central SBC with centralized trunks serving all branches, and a proxy SBC paired with Teams through its external IP with downstream branch SBCs that communicate over internal IPs and are not directly visible to Teams Phone. in context
• With Local Media Optimization a user might hear a few seconds of silence while a call is being established, which Microsoft attributes to the complexity of the architecture. in context
• A Teams client is not identified as internal when its public IP matches the trusted IP list but its subnet matches no network site; Local Media Optimization requires a matching network site for every connection from a listed trusted IP. in context
• Calls involving voice apps such as Auto Attendant and Call Queue are not optimized by Local Media Optimization and flow through the proxy SBC, except transfers from an Auto Attendant to an LMO user, which follow the optimized path as a direct 1:1 call. in context

Cite this source record

APA

WarmTransfer. (2026, September 10). Local Media Optimization for Direct Routing. WarmTransfer. https://warmtransfer.net/knowledge/sources/ms-learn-dr-media-optimization

BibTeX

@misc{warmtransfer-ms-learn-dr-media-optimization,
  title  = {Local Media Optimization for Direct Routing},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/sources/ms-learn-dr-media-optimization},
  note   = {Microsoft, accessed 2026-09-30}
}