01
Modernize Enterprise Voice
Move users from PBX and legacy telephony to Microsoft Teams while preserving external voice connectivity and operational continuity.
Use Case — Microsoft Teams Direct Routing
Secure Microsoft Teams voice with Sentinel SBC architecture.
Microsoft Teams is the collaboration layer. The Session Border Controller is the secure voice control layer. M5 Technologies helps organizations connect Teams Phone to SIP trunks, PSTN services, carriers, legacy PBXs, contact centers and enterprise voice infrastructure using Sentinel SBC platforms.
Teams Voice Edge
TEAMS • TLS/SRTP • SBC • SIP TRUNKS • PSTN
DIRECT ROUTING
SIP SECURITY
CARRIER CHOICE
PBX MIGRATION
TeamsCloud collaboration
SBCSecure voice edge
SIPCarrier connectivity
Secure Voice EdgeProtect Teams voice with TLS, SRTP, topology hiding and SIP normalization.
Carrier FlexibilityConnect to preferred SIP carriers and regional telecom providers.
Hybrid MigrationBridge Teams with PBXs, contact centers and legacy voice systems.
Enterprise ControlControl routing, policies, interoperability and voice continuity.
The business use case
Teams Phone becomes enterprise-ready when the voice edge is controlled.
Organizations adopt Microsoft Teams to unify collaboration, calling and meetings. But enterprise voice is not only a cloud license. It requires secure SIP interconnection, PSTN access, carrier choice, emergency routing, migration planning, resiliency and interoperability with existing systems.
02
Control Carriers & Costs
Keep control over SIP carriers, phone numbers, regional routing and telecom economics instead of being locked into a narrow model.
03
Secure the SIP Border
Use the Sentinel SBC as the demarcation point between Microsoft Teams, carriers, PBXs, contact centers and external voice networks.
Technical schematic
Microsoft Teams Direct Routing architecture with Sentinel SBC.
The SBC is the secure interconnection point between Microsoft Teams and external telephony. It provides SIP security, routing intelligence, interoperability, policy control and visibility.
Microsoft Teams
Teams Phone users, collaboration, meetings and cloud voice services.
Sentinel SBC
TLS/SRTP, topology hiding, SIP normalization, routing and policy control.
SIP / PSTN Network
SIP trunks, carriers, PBX, contact center, emergency routing and PSTN access.
Security architecture
Why Microsoft Teams voice needs a real SBC security layer.
Teams Direct Routing exposes a critical voice boundary. Sentinel SBCs help protect that boundary while enabling interoperability with SIP trunks, carriers and enterprise voice systems.
TLS SignalingSecure SIP signaling between Teams and the SBC to reduce exposure of voice-session control traffic.
SRTP MediaEncrypted media transport for protected voice communications across the Teams voice edge.
Topology HidingConceal internal voice architecture from external networks and carriers.
SIP NormalizationAdapt and normalize SIP behavior between Teams, carriers, PBXs and other voice systems.
Policy ControlApply routing, session and access policies at the voice border.
Diagnostics & VisibilityImprove troubleshooting for registration, routing, media and interoperability issues.
Calling model comparison
Microsoft Calling Plan vs Direct Routing with Sentinel SBC.
Direct Routing provides greater flexibility and control for organizations with complex carrier, PBX, geographic, cost or migration requirements.
| Capability | Microsoft Calling Plan | Direct Routing + Sentinel SBC | Business Impact |
|---|---|---|---|
| Carrier Choice | Limited to available Microsoft plans and regions | Use preferred SIP carriers and regional providers | More control over cost, routing and telecom strategy |
| SIP Trunk Integration | Limited | Full SIP trunk integration through SBC | Preserve existing carrier contracts and trunking architecture |
| PBX Coexistence | Limited | Supports migration and coexistence with PBX systems | Reduce migration risk and avoid forced rip-and-replace |
| Contact Center Integration | Limited depending on architecture | Can support broader SIP and contact center interconnection | Better fit for complex enterprise voice environments |
| Voice Security Control | Less customer-controlled | Controlled SBC layer with SIP security policies | Greater visibility and demarcation at the voice edge |
| Geographic Flexibility | Region-dependent | Flexible by SIP carrier and SBC deployment strategy | Better alignment with global and multi-site requirements |
Sentinel SBC portfolio
Choose the right Sentinel SBC for your Teams voice environment.
Sentinel platforms support different deployment profiles, from smaller branch environments to virtual and large-scale service provider architectures.
| Platform | Deployment Type | Best Fit | Typical Teams Use Case | Key Advantage |
|---|---|---|---|---|
| Sentinel Mini | Compact hardware appliance | Small offices and focused deployments | Branch Direct Routing, small user groups, remote sites | Compact footprint with secure Teams voice edge |
| Sentinel 100 | Hardware appliance | SMB and branch environments | Distributed enterprise voice and regional offices | Balanced capacity, control and deployment simplicity |
| Sentinel 400 | Higher-capacity appliance | Enterprise headquarters and larger sites | Multi-site aggregation, higher-density Teams voice | Greater scale for enterprise Direct Routing |
| Sentinel CS / DGW50 | Virtual SBC software | Virtualized, cloud-aligned and service provider deployments | Large-scale Teams voice, managed services and virtual SBC architecture | Software-driven scalability and deployment flexibility |
Industries and environments
Where Teams Direct Routing creates enterprise value.
Teams Direct Routing is valuable wherever organizations need secure, controlled and flexible voice architecture across users, sites, carriers and operational environments.
Deployment journey
How a Teams Direct Routing project typically works.
A successful deployment aligns cloud collaboration goals with real-world voice, routing, security, carrier and migration requirements.
1. AssessReview users, carriers, PBX dependencies, sites, numbering and migration goals.
2. ArchitectDesign Teams, SBC, SIP trunk, routing, security and resiliency architecture.
3. SelectChoose Sentinel Mini, 100, 400 or Sentinel CS based on scale and topology.
4. ValidateTest call flows, carrier behavior, emergency routing, failover and interoperability.
5. ScaleRoll out across users, regions, sites and managed voice environments.
Why not deploy Teams voice without a real SBC?
Voice without border control creates risk.
A Direct Routing architecture without a controlled SBC layer can create operational blind spots, security exposure and migration complexity.
Without a proper SBC layer
- Limited SIP normalization and interoperability control.
- Reduced visibility into call failures and signaling behavior.
- Carrier lock-in or fragmented regional routing strategy.
- Weaker voice-edge demarcation and security policy enforcement.
- Harder migration from PBX, contact center and legacy voice systems.
With Sentinel SBC architecture
- Secure Teams voice edge using TLS, SRTP and topology hiding.
- Controlled SIP routing, normalization and policy management.
- Carrier flexibility and multi-provider architecture support.
- Better troubleshooting, visibility and operational discipline.
- Cleaner enterprise migration from legacy voice to Teams.
FAQ
Microsoft Teams Direct Routing use case questions.
What is Microsoft Teams Direct Routing?
Direct Routing connects Microsoft Teams Phone to SIP trunks, PSTN services and enterprise telephony infrastructure through a Session Border Controller.
Why is a Session Border Controller required?
The SBC secures the voice edge, normalizes SIP, controls routing, protects topology and enables interoperability between Teams and external networks.
Can Sentinel SBCs support carrier flexibility?
Yes. Sentinel SBCs help organizations connect Teams to preferred SIP carriers and preserve regional routing and telecom strategy.
Can Direct Routing help migrate from a PBX?
Yes. Direct Routing can support coexistence and phased migration from PBX environments into Teams voice.
Which Sentinel SBC should I choose?
The right model depends on scale, user count, sites, topology, virtual or hardware preference, and service provider requirements.
Can M5 help design the architecture?
Yes. M5 Technologies can help evaluate voice infrastructure, model selection, SIP integration, security and deployment strategy.
Teams voice assessment
Build a Microsoft Teams voice architecture that fits your business.
Whether you are migrating from PBX, integrating SIP trunks, connecting branches or building managed Teams voice services, M5 Technologies can help define the right Sentinel SBC strategy.
- Sentinel SBC platform selection
- Microsoft Teams Direct Routing architecture
- SIP trunk, carrier and PSTN integration
- PBX migration and hybrid voice planning
- Teams voice security and interoperability review