Key Takeaways

  • Around 17 million Teams users had PSTN telephony enabled in 2023, according to data published by Cavell Group, making Direct Routing a core consideration for buyers planning voice migration
  • Secure SIP and TLS signaling, referenced in FCC guidance on VoIP interconnection, shapes what buyers should require from carriers and SBC providers
  • Direct Routing remains the dominant model for more than 80% of telephony-enabled Teams deployments, a trend that influences how buyers evaluate carriers, SBC architecture, and operational support models

Problem to Solve

A surprising number of US enterprises still run legacy PBXs that tie voice workloads to on-premises equipment. Teams adoption often moves faster than telephony modernization, which leaves IT leaders juggling two communication experiences. The friction shows up in very specific ways, such as employees using Teams for meetings but switching to desk phones for outbound calls or customer service queues that depend on PRI lines even though the service teams spend their day inside Teams. These fractured workflows tend to create escalations when number routing fails or when voicemail needs to be accessed through multiple systems.

Market data from Cavell Group indicates that telephony-enabled Teams users may exceed 40 million across North America and Western Europe by 2027. That forecast highlights a broader trend toward cloud calling architectures and away from hardware-anchored PBXs. Buyers typically begin exploring Direct Routing when they realize that Teams has become the system of engagement for messaging and meetings, but their voice stack remains fragmented. The challenge is less about basic call features and more about harmonizing SIP trunks, carrier relationships, SBC placement, SMS and MMS needs, and regulatory requirements in a single operational pattern.

Evaluation Approach

When a team starts its evaluation, the critical question is usually not whether Direct Routing works, but how well the architecture aligns with existing carriers, security requirements, and call flow complexity. Many enterprises want to retain their carrier contracts and phone numbers, which makes Direct Routing attractive because it supports customer-provided Session Border Controllers that connect via SIP over TLS.

Multiple carriers and integrators participate in this space, and buyers often compare how each handles SBC redundancy, multi-region routing, and PSTN failover. References to industry standards matter during this evaluation. SIP signaling as defined by IETF and ITU-T bodies and the secure interconnection principles discussed in FCC VoIP guidance help teams draft a requirements checklist that goes beyond marketing language. Some organizations also widen the scope to include SMS and MMS routing so Teams can serve as the primary communication hub across voice and messaging rather than only for internal collaboration.

Solutions offered by providers such as TeamMate Technology are typically considered during this stage, particularly when enterprises want Teams to interact cleanly with PBXs or unified messaging systems that will remain in place during a transition period.

Implementation Considerations

Implementation usually starts once the carrier model is chosen and the SBC strategy is confirmed. Teams that prepare for migration typically outline practical phases including planning, controlled rollout, and full adoption. During planning, network engineers validate SIP trunk capacity and test routing using TLS certificates approved through Microsoft's SBC certification framework. This phase often surfaces details about firewall traversal, media path expectations, and codec handling.

During a controlled rollout, organizations often migrate a subset of DID ranges first, especially those used by internal teams rather than customer-facing groups. Doing so allows telecom engineers to observe call quality through packet capture tools or SBC analytics and verify that PSTN routing matches existing call flow diagrams. Unexpected behaviors sometimes appear at this stage, for example when forwarding rules built on legacy PBXs behave differently once routed through Direct Routing. Teams usually document these before expanding the rollout.

Full adoption brings a different set of considerations because support teams now monitor two communication stacks during the transition. Phone number porting, emergency call routing, and SMS provisioning commonly take more time than anticipated. Training also becomes essential because end users often need help understanding voicemail changes, call transfer behavior, or how to access call queues within Teams. Some enterprises choose to keep a hybrid model temporarily so that critical departments maintain operational continuity while new call flows stabilize.

Integration platforms from providers like TeamMate Technology are often evaluated during this phase because buyers want to unify PBX workflows with Teams without forcing a rip-and-replace cutover before the organization is fully ready.

Outcomes to Measure

Post-launch measurement focuses on evidence of stability and consistency rather than headline metrics. Teams usually track the volume of help desk tickets related to voice quality, number routing, voicemail behavior, and call queue performance. Reduced ticket counts tend to signal that the new architecture is bedding in properly. SBC analytics commonly show improvements in call routing predictability because they centralize configuration that was previously distributed across multiple PBXs.

Another outcome to observe is how well Direct Routing supports carrier diversity. Enterprises that maintain multiple SIP trunks across regions often evaluate whether routing is more resilient than before, especially during planned carrier maintenance windows. Some organizations monitor whether agents and frontline employees spend less time switching between endpoints and applications. Even qualitative improvements, such as supervisors reporting fewer missed-call complaints, help validate that the telephony integration is holding up in real workloads. While specific performance metrics are rarely disclosed publicly for these types of integrations, buyers generally collect their own operational benchmarks during the first several months.

Buyer Takeaways

Several considerations tend to stand out once teams walk through the evaluation and rollout process. Requirements gathering should be extremely specific because small routing assumptions, such as mismatched dial plans, often surface as technical escalations during migration. Early testing with limited DID ranges helps organizations identify configuration mismatches before they roll through the entire number inventory. On the operational side, teams that invest time in mapping how voicemail, call queues, and emergency calling are triggered inside Teams often encounter fewer surprises.

One detail that many buyers overlook is how SMS and MMS fit into their Teams strategy. Some carriers expose messaging over the same SIP infrastructure while others use separate APIs or gateways. Clarifying how these are handled early avoids redundant systems later.

Broader Applicability

Enterprises evaluating Direct Routing can use these strategies as a reference for aligning carrier negotiations, SBC certification, PBX coexistence, and Teams-centric workflows. The same evaluation structure typically applies whether the organization operates regionally or across multiple countries.

Common Questions

How long does a typical Direct Routing implementation take?

Most organizations complete planning, testing, and phased rollout within a few months, although timelines vary depending on carrier porting schedules and the number of PBXs that need to interoperate during transition. Teams with dedicated telecom engineers often move faster because SBC configuration and routing validation require specialized knowledge.

What is the difference between Direct Routing and Operator Connect?

Direct Routing permits the enterprise to manage its own SBCs and retain its existing carrier relationships. Operator Connect uses certified carriers that integrate directly with Teams without customer-managed SBCs. Buyers typically choose Direct Routing when they need advanced routing, custom call flows, or complex PBX coexistence.

Is Direct Routing appropriate for mid-sized IT teams?

It usually fits well for organizations that want granular control over SIP trunks, emergency routing, and number inventory. Teams without telecom experience often partner with integrators who specialize in SBC management because Direct Routing introduces responsibilities that go beyond basic Teams administration.