Microsoft Teams Calling: Direct Routing and Phone Plans Explained

Why Businesses are Moving Calling into Teams

Microsoft Teams has become the primary communication platform for many UK businesses — used daily for meetings, messaging, and file sharing. Adding calling to Teams consolidates all communications into a single application, reducing the number of tools employees need to manage and improving the experience for remote and hybrid workers who do not have access to a physical desk phone.

Microsoft Teams Phone has surpassed 26 million PSTN users worldwide as of December 2025 — up from 20 million in April 2024, representing 30% growth in 20 months. (UC Today)

92% of hybrid workers rely daily on Microsoft 365 or Teams for communication and data access. (SQ Magazine)

28% of UK employees work in a hybrid setup (office + home); 16% are fully remote (ONS 2025). (Mollearn)

Traditional PBX hardware ages, requires specialist maintenance, and is increasingly difficult to integrate with modern workflows. Teams Phone replaces this hardware-based telephony with a cloud-based solution that is maintained by Microsoft, scales easily, and provides the same experience on any device or location.

Direct Routing: Maximum Flexibility

Direct Routing connects Teams Phone to the public telephone network via a Session Border Controller (SBC) — a hardware or virtual appliance that acts as the bridge between Teams and a telephony carrier of your choice. This approach provides maximum flexibility: you can choose any Direct Routing-certified carrier for your call minutes, port your existing numbers from any provider, and maintain complex call routing configurations.

Direct Routing is typically the right choice for businesses with existing telephony infrastructure they need to integrate with during transition, complex call routing requirements, or high call volumes where selecting a competitive carrier independently provides meaningful cost benefit. AMVIA provides Direct Routing services and manages the SBC configuration and carrier relationship on your behalf.

Operator Connect: Simplified Integration

Operator Connect is a simpler model where a Microsoft-certified operator — AMVIA is one — provides calling capability directly through the Microsoft Teams admin centre. There is no SBC hardware to manage. Numbers are assigned and calling plans configured entirely within Teams administration. Setup is faster and requires less technical infrastructure than Direct Routing.

Operator Connect is well-suited to businesses that want a straightforward Teams Phone deployment without the complexity of managing SBC infrastructure. AMVIA's Operator Connect service includes number porting, calling plans, and support managed through a single provider relationship.

Microsoft Calling Plans

Microsoft also offers its own calling plans — bundles of minutes purchased directly through Microsoft 365 licensing. These are available for domestic calls, international calls, and pay-as-you-go options. Microsoft Calling Plans are the simplest option to deploy but may be more expensive than Direct Routing or Operator Connect for businesses with significant call volumes, and offer less flexibility in number porting.

AMVIA can help compare the total cost of Microsoft Calling Plans against Direct Routing and Operator Connect based on your actual call volumes and number requirements, so you choose the most cost-effective model rather than defaulting to the simplest setup.

Number Porting and Transition

Retaining your existing business numbers during a Teams Phone migration is almost always possible. AMVIA manages the number porting process — coordinating with your current provider and Microsoft to transfer numbers to Teams Phone without service interruption. The cutover is typically scheduled for a low-traffic period and tested before going live.

Where you have geographic numbers, non-geographic numbers (0800, 03xx), or complex hunt groups, AMVIA maps the current configuration to the Teams Phone equivalent before migration. Auto-attendants and call queues in Teams replicate the functionality of traditional PBX hunt groups and IVR menus.

Microsoft 365 Licensing for Teams Phone

Teams Phone requires a Phone System licence. This is included in Microsoft 365 E5 but must be added separately to Business Premium, E3, and other plans. AMVIA advises on licensing requirements based on your current licence estate and the calling option chosen. For businesses not currently on Business Premium or above, the security benefits of upgrading often justify the licence cost independent of the telephony requirement.

Quality of Service for Teams Calling

Voice call quality over Teams Phone depends on the quality of your internet connection. Latency, jitter, and packet loss all affect call clarity. AMVIA assesses your connectivity as part of Teams Phone deployment and recommends quality-of-service (QoS) configuration on your network equipment to prioritise voice traffic. For businesses on managed connectivity from AMVIA, QoS can be applied end-to-end across the connection.