01
Teams Phone integration
Enable Microsoft Teams users to place and receive PSTN calls through a secure SBC and SIP trunking architecture while centralizing enterprise collaboration and voice workflows.
M5 Technologies • Microsoft Teams Direct Routing • Teams SBC
Connect Microsoft Teams Phone to your enterprise voice network securely.
M5 Technologies helps enterprises, service providers, government organizations and critical infrastructure operators deploy Microsoft Teams Direct Routing using Sentinel CS Virtual SBC, Sentinel 100 and Sentinel 400 for secure PSTN connectivity, SIP trunking, hybrid PBX integration, TLS, SRTP and resilient Teams Voice migration.
Teams VoiceEnable Microsoft Teams Phone with enterprise-grade PSTN connectivity.
Teams SBCUse Sentinel SBCs as the secure SIP demarcation layer.
Hybrid MigrationIntegrate existing PBXs, SIP trunks, carriers and cloud voice services.
Secure by DesignTLS, SRTP, SIP normalization, topology hiding and policy control.
Teams Voice LayerTeams • SBC • SIP • PSTN
M5 Teams SBC Core
Sentinel CS • Sentinel 100 • Sentinel 400
Teams
TLS
SRTP
PSTN
Direct RoutingTeams Phone to SIP trunks and carriers
Hybrid PBXCoexistence for phased migration
HA / DRResilient voice architecture design
Teams Direct RoutingConnect Microsoft Teams Phone to PSTN, carriers and SIP trunks.
Sentinel CSVirtual SBC for scalable enterprise, service provider and cloud voice deployments.
Sentinel 100Enterprise SBC platform for controlled SIP security and Direct Routing environments.
Sentinel 400SBC plus media gateway architecture for hybrid PBX and legacy voice integration.
Secure Teams VoiceTLS, SRTP, SIP normalization, topology hiding and routing policy.
What is Direct Routing?
Microsoft Teams Direct Routing connects Teams Phone to the public telephone network through an SBC.
Microsoft Teams Direct Routing allows organizations to use Microsoft Teams as their enterprise voice platform while maintaining control over PSTN connectivity, SIP trunks, existing carriers, numbering plans, emergency routing, PBX coexistence, compliance and migration strategy. Instead of relying only on a bundled calling plan, Direct Routing uses a Session Border Controller to securely connect Microsoft Teams Phone with the organization’s telecom environment.
For many enterprises, Teams Direct Routing is the most flexible path to cloud voice because it preserves the ability to choose carriers, integrate legacy PBXs, maintain existing contracts, support complex routing and control how users, locations and critical voice services move into Microsoft Teams. M5 Technologies positions Sentinel SBC solutions as the secure voice infrastructure layer between Microsoft Teams Phone, SIP trunks, PBXs, carriers and operational voice systems.
02
PSTN connectivity control
Keep control over carriers, DID numbers, routing rules, cost models, country-specific voice policies and service provider relationships.
03
SBC security requirement
Use a Session Border Controller to secure SIP signaling and media, normalize traffic, protect topology and enforce routing policy between Teams and the voice network.
Why enterprises choose Direct Routing
Direct Routing gives IT and telecom teams control over the voice migration.
Enterprises rarely move to Teams Voice in a single step. They often have existing PBXs, analog gateways, contact centers, SIP trunks, emergency calling requirements, regional telecom contracts, public-sector procurement constraints and operational sites that cannot be disrupted. Direct Routing allows the organization to modernize voice while preserving control over the network, routing and migration timeline.
Strategic reasons
Teams Direct Routing is selected when an organization wants flexibility and control instead of a rigid, one-size-fits-all calling model.
Use preferred SIP trunks, carriers and telecom contracts
Support multi-site and multi-country routing strategies
Preserve hybrid PBX coexistence during migration
Maintain control over emergency routing and compliance needs
Design high availability and disaster recovery for voice services
Technical reasons
The SBC layer gives telecom teams the technical controls needed to connect cloud collaboration with real-world voice networks.
TLS encryption for SIP signaling
SRTP support for secure media
SIP normalization between Teams, carriers, PBXs and gateways
Topology hiding and policy-based routing
Interoperability control for complex voice environments
Teams architecture diagrams
How M5 Sentinel SBC solutions connect Microsoft Teams to enterprise voice.
The following diagrams explain the M5 architecture for Teams Direct Routing. They are built with HTML and CSS so the labels remain readable in Shopify and mobile layouts.
1. Microsoft Teams Direct Routing overview
The Sentinel SBC sits between Microsoft Teams Phone and the enterprise PSTN or SIP trunking environment, securing and controlling the voice path.
Cloud Side
Microsoft Teams Phone
Teams users, Teams Phone System, collaboration, calling policies and cloud voice services.
M5 Technologies
Sentinel SBC Layer
TLS, SRTP, SIP normalization, topology hiding, routing policy and secure demarcation.
Voice Network
SIP Trunk / Carrier / PSTN
Enterprise carrier connectivity, PSTN access, DID routing and voice termination.
Microsoft Teams Direct RoutingTeams SBCTeams Phone SystemTeams PSTN Connectivity
© M5 TechnologiesMicrosoft Teams Direct Routing Architecture
2. Hybrid PBX and Teams coexistence architecture
Most enterprises need a transition period where Teams Phone, legacy PBX systems, analog gateways and SIP trunks coexist. Sentinel SBC solutions create the controlled interconnection layer.
Cloud Users
Microsoft Teams Phone
Users migrated to Teams Voice with Direct Routing.
Legacy Users
Existing PBX / UC Platform
Sites, departments or functions that remain on legacy telephony during transition.
M5 SBC Layer
Sentinel CS / Sentinel 100 / Sentinel 400
Routes calls, normalizes SIP, protects the edge and enables coexistence across platforms.
Carrier Side
SIP Trunks and PSTN
Preferred carrier services and PSTN connectivity.
Legacy Side
Gateways / Analog / Branch Voice
Analog devices, branch PBXs, emergency phones or specialized voice systems.
Hybrid PBX IntegrationCarrier IntegrationTeams MigrationSIP Normalization
© M5 TechnologiesM5 Teams Hybrid Voice Architecture
3. Sentinel CS Virtual SBC deployment
Sentinel CS supports scalable virtual SBC deployment for enterprises, service providers and high-capacity Teams voice environments.
Cloud Voice
Microsoft Teams Phone
Teams users and Teams Phone policies.
M5 Virtual SBC
Sentinel CS
Virtualized SBC for scale, redundancy, carrier edge and centralized voice control.
Network
SIP Trunks / Service Provider
Carrier connectivity and PSTN access.
Result
Scalable Teams Direct Routing
Designed for large enterprises, operators and critical communications environments.
© M5 TechnologiesSentinel CS Teams Direct Routing Flow
4. Sentinel 400 hybrid SBC + gateway model
Sentinel 400 is relevant when Teams Direct Routing must coexist with legacy voice interfaces, PBX systems or gateway requirements.
Enterprise Side
PBX / Legacy Voice / Analog
Existing telephony systems that still require integration.
M5 Platform
Sentinel 400
SBC plus media gateway architecture for hybrid enterprise voice migration.
Cloud and Carrier
Teams Phone + SIP Trunks
Cloud voice and PSTN connectivity in one controlled architecture.
Result
Controlled migration path
Move users and sites to Teams without abandoning necessary legacy integrations.
© M5 TechnologiesSentinel 400 Hybrid Teams Architecture
M5 Sentinel portfolio
Choose the right Sentinel SBC for your Teams Direct Routing deployment.
M5 Technologies supports multiple Teams voice architectures. The right platform depends on scale, topology, virtualization strategy, carrier model, gateway requirements and whether the organization needs pure SBC functionality, hybrid media gateway capabilities or service-provider-grade deployment flexibility.
CS
Sentinel CS Virtual SBC
Virtual SBC platform for scalable Teams Direct Routing, enterprise data centers, private cloud, service provider environments, high availability and centralized SIP control.
100
Sentinel 100
Enterprise SBC platform for organizations that need secure SIP demarcation, Teams connectivity, trunk control and reliable voice infrastructure in a compact architecture.
400
Sentinel 400
Hybrid SBC and media gateway architecture for Teams Direct Routing deployments that also require legacy PBX, analog, digital or gateway integration.
Security and resilience
Teams Voice must be protected like core enterprise infrastructure.
Voice is no longer isolated on traditional telephony circuits. When Teams Phone connects to SIP trunks and carrier networks, security must be designed into the voice edge. Sentinel SBC solutions provide the policy, encryption, routing and demarcation layer needed to protect enterprise voice.
Security controls
TLS for encrypted SIP signaling between Teams, SBCs and supported voice peers
SRTP support for secure media where applicable in the voice architecture
SIP normalization to resolve interoperability differences between Teams, carriers and PBXs
Topology hiding to avoid exposing internal voice infrastructure
Policy-based call routing, trunk control and traffic validation
Continuity controls
High availability design for enterprise and service provider voice environments
Disaster recovery architecture for carrier, site or platform failure scenarios
Redundant SIP trunks, SBC pairs and routing strategies
Hybrid PBX coexistence to avoid disruptive big-bang migration
Operational visibility for troubleshooting Teams Voice and PSTN issues
Deployment models
Flexible Teams Direct Routing for enterprise, carrier and critical infrastructure networks.
Microsoft Teams Direct Routing can be deployed in several ways depending on the organization’s control requirements, regional structure, carrier strategy and resilience objectives.
A
Enterprise on-premise
Deploy Sentinel SBCs at enterprise sites or data centers for local SIP trunking, PBX coexistence and controlled Teams Phone migration.
B
Private cloud / virtual SBC
Use Sentinel CS Virtual SBC to centralize Teams Direct Routing in private cloud or virtual infrastructure while maintaining enterprise control.
C
Service provider model
Support carrier or hosted voice providers delivering Teams Direct Routing to multiple customers or enterprise tenants.
D
Hybrid PBX migration
Allow Teams Phone and legacy PBXs to coexist during a phased migration by using the SBC as the routing and interoperability layer.
E
Critical infrastructure
Design Teams Voice with attention to continuity, emergency routing, operational sites, high availability and cybersecurity.
F
Multi-carrier architecture
Connect multiple SIP trunks, regions or carriers through controlled policies to reduce dependency and improve routing flexibility.
Competitive comparison
Direct Routing versus alternative Teams voice approaches.
Every organization has different voice requirements. The table below helps position Direct Routing and M5 Sentinel SBC architecture against simpler or less flexible approaches.
| Criteria | Microsoft Calling Plans | Basic Operator Connect / Hosted Voice | M5 Teams Direct Routing Architecture |
|---|---|---|---|
| Carrier control | Limited to available plans and supported regions. | Carrier control depends on provider model and service scope. | Strong control Use preferred SIP trunks, carriers and negotiated enterprise telecom contracts. |
| SBC control | No customer-controlled SBC layer. | Usually provider controlled, with less direct customer control. | Customer or provider controlled Sentinel SBC provides demarcation, policy, routing and security. |
| Hybrid PBX integration | Limited for complex PBX coexistence environments. | Possible depending on provider but often less flexible. | Designed for coexistence Integrate Teams, PBXs, gateways, analog services and SIP trunks. |
| Security control | Cloud service managed; limited customer voice edge controls. | Provider-dependent controls. | SBC-grade controls TLS, SRTP, topology hiding, SIP normalization and policy enforcement. |
| Disaster recovery | Limited control over alternate carriers and routing strategies. | Provider-dependent DR architecture. | Flexible DR design Redundant SBCs, carriers, trunks and routing plans. |
| Best fit | Small or simple Teams Phone environments. | Organizations wanting a managed provider model. | Enterprises, service providers, government and critical infrastructure operators needing control. |
Business benefits
Move to Teams Voice without losing telecom control.
M5 Teams Direct Routing solutions help organizations modernize collaboration and telephony while keeping the carrier, routing, security and continuity controls that matter in enterprise and critical environments.
01
Lower migration risk
Move users, sites and departments to Teams Voice in phases while preserving PBX coexistence and operational continuity.
02
Carrier flexibility
Use existing SIP trunk providers, negotiate better telecom costs and maintain regional voice strategies.
03
Enterprise security
Protect the Teams voice edge with TLS, SRTP, SIP policy, topology hiding and SBC-grade demarcation.
04
Operational continuity
Design HA, DR, alternate routing and fallback models for enterprise voice and critical operations.
05
Interoperability
Normalize SIP across Teams, PBXs, carriers, gateways and specialized enterprise voice systems.
06
Scalable architecture
Support small deployments, large enterprises and service provider environments using the appropriate Sentinel SBC platform.
Migration strategy
A practical path from legacy voice to Microsoft Teams Direct Routing.
Successful Teams Voice migration requires more than licensing. It requires a precise telecom architecture, validated call flows, emergency routing review, SIP interoperability testing and a phased adoption model.
Step 1
Assess voice estate
Inventory PBXs, SIP trunks, carriers, DIDs, call flows, analog devices and user groups.
Step 2
Design SBC architecture
Select Sentinel CS, Sentinel 100 or Sentinel 400 based on scale and topology.
Step 3
Validate SIP and security
Test TLS, SRTP, SIP normalization, carrier routing, emergency calling and PBX coexistence.
Step 4
Migrate users in phases
Move sites, groups and numbers to Teams Phone while monitoring voice quality and continuity.
Result
Secure Teams Voice operation
A controlled Direct Routing environment with documented call flows, routing and support model.
© M5 TechnologiesM5 Teams Direct Routing Migration Framework
FAQ
Frequently asked questions about Microsoft Teams Direct Routing.
What is Microsoft Teams Direct Routing?
Direct Routing connects Microsoft Teams Phone to the public telephone network using a Session Border Controller and SIP trunking or carrier connectivity.
Why is an SBC required?
The SBC acts as the secure voice border between Microsoft Teams and SIP networks. It manages routing, TLS, SRTP, SIP normalization, topology hiding, policy and interoperability.
Which M5 products are used?
M5 deployments can use Sentinel CS Virtual SBC, Sentinel 100 or Sentinel 400 depending on scale, virtualization requirements, gateway needs and hybrid voice architecture.
Can M5 support hybrid PBX migration?
Yes. Sentinel SBC solutions can connect Teams Phone with existing PBXs, SIP trunks, gateways and carriers so organizations can migrate in phases.
Does Direct Routing support existing carriers?
Yes. One of the major reasons enterprises choose Direct Routing is the ability to use preferred SIP trunks and carrier relationships.
How does M5 address security?
M5 Sentinel SBC architecture supports secure signaling and media design, including TLS, SRTP, topology hiding, SIP normalization, traffic policy and controlled demarcation.
Is Teams Direct Routing suitable for government?
Yes. Government and public-sector organizations often choose Direct Routing when they need carrier control, migration flexibility, voice continuity, security and compliance-sensitive routing.
What should be assessed before migration?
Assess PBXs, SIP trunks, DID inventory, call flows, emergency routing, analog endpoints, carrier contracts, locations, user groups, network readiness and high-availability requirements.
Free Teams Voice Assessment
Plan your Microsoft Teams Direct Routing architecture before migration starts.
Share your Teams Phone goals, SIP trunk environment, PBX estate, carrier requirements, locations, user count and security objectives. M5 Technologies can help evaluate the right Sentinel SBC architecture for your Teams Voice deployment.