Direct Routing for Microsoft Teams Phone System enables organizations to use their own session border controller (SBC) and SIP trunks to connect Teams to the PSTN.  This approach has several advantages including:

  • Cost savings compared to Microsoft’s Calling Plan
  • Flexibility to support call routing to other cloud-based or on-premises platforms (e.g. for contact center)
  • Maintaining ownership of phone numbers
  • Easier migration by eliminating the need to port phone numbers to Microsoft

Nemertes analysis of PSTN access costs for Microsoft Teams users found that companies using Direct Routing pay on average $7.91 per month, per phone number for local calling services (with additional charges for long-distance). Compared with the list pricing of $12 per-month per user for Microsoft’s own Calling Plan (for 3,000 US domestic minutes of 1,200 EU domestic minutes), the cost savings for Direct Routing can be substantial though buyers should be careful to also assess design, setup, hardware, and on-going maintenance costs when evaluating the costs of a Direct Routing solution.

In addition, Calling Plan customers on average only use 50-75% of purchased minutes, meaning most Calling Plan customers are paying for minutes that they aren’t using.

As a result, Nemertes found that 89% of those adopting Microsoft Teams Phone System were using, or planning to use, Direct Routing with the highest adoption concentrated among mid and large-size organizations.

Adopting Direct Routing as part of a migration to Microsoft Teams Phone System means picking the right SBC and SIP trunking partner. With regard to SBCs, Teams Phone System users have several options including:

  • Maintain existing, or purchase new, appliance-based SBCs
  • Implement self (or MSP) – managed virtual SBCs within owned data centers or hosted in the cloud
  • Leverage a cloud-based SBC-as-a-Service (SBCaaS)

Today, the majority (85.7%) of organizations use their own hardware-based SBCs. However, SBC deployments are rapidly shifting to the cloud with 17.9% saying they prefer to leverage SBCaaS and just 46.4% planning to maintain on-premises appliances.

SBCaaS, purchased as part of a SIP trunking service, enables organizations to shift their entire communications infrastructure to the cloud, eliminating the need to maintain on-premises infrastructure. Integrated SBCaaS and SIP trunking services reduce deployment time and simplify management providing a single bill and support structure.

Selecting the right SBCaaS as part of a direct routing implementation requires evaluating the provider’s architecture.  Those who run their SBCaaS inside of Microsoft Azure are able to natively connect to Microsoft Teams without requiring cloud-to-cloud integration (with potential additional complexity and delay).  In addition, providers differ in the way they provision SBCs with using a multitenant model to reduce while others rely on single-tenant deployments. Single tenet approaches require custom creation and configuration of separate SBC instances for each customer. Multitenant approaches enable configuration of automated, repeatable deployments, leading to faster turn-up times, and reduced management cost and complexity.

Direct Routing offers those adopting Microsoft Teams Phone System the ability to achieve the benefits of cloud deployment while minimizing cost and complexity. Consider providers that offer Azure-based, multi-tenant, SBCaaS integrated with SIP trunking services for PSTN access. 


About Nemertes: Nemertes is a global research-based advisory and consulting firm that analyzes the business value of emerging technologies. Since 2002, we have provided strategic recommendations based on data-driven operational and business metrics to help organizations deliver successful technology transformation to employees and customers. Simply put: Nemertes’ better data helps clients make better decisions.


Irwin Lazar – Vice President & Service Director

Research Leader: Digital Workplace
Primary Focus Areas: Unified Communications, VOIP/IP Telephony, Video/Audio/Web Conferencing, Team Collaboration, SIP trunking, Session Border Control, UC-as-a-Service, UC Operations, Management, and Business Value Measurement
Other Areas of Expertise: Network Communication and Services, Mobility and Mobile Security, Contact Center and Customer Engagement, SDN/SD-WAN.
Irwin Lazar develops and manages research projects, conducts and analyzes primary research, and advises enterprise and vendor clients on technology strategy, adoption and business metrics, Mr. Lazar is responsible for benchmarking the adoption and use of emerging technologies in the digital workplace, covering enterprise communications and collaboration as an industry analyst for over 20 years.

A Certified Information Systems Security Professional (CISSP) and sought-after speaker and author, Mr. Lazar is a blogger for and contributor for writing on topics including team collaboration, UC, cloud, adoption, SD-WAN, CPaaS, WebRTC, and more. He is a frequent resource for the business and trade press and is a regular speaker at events such as Enterprise Connect, InfoComm, and FutureIT. In 2017 he was recognized as an Emerging Technologies Fellow by the IMCCA and InfoComm.

Mr. Lazar’s earlier background was in IP network and security architecture, design, and operations where he advised global organizations and held direct operational responsibility for worldwide voice and data networks.