Microsoft Teams has become the collaboration backbone for millions of businesses worldwide, supporting chat, meetings, and internal communication across every industry. Yet despite its rapid adoption and deep integration into the workday, external calling remains significantly underused. While Teams is the daily communication hub, many organizations still rely on legacy telephony systems for outbound and inbound PSTN calling.
This gap represents both a missed opportunity and a strategic risk for organizations moving toward cloud-first communication. If Teams has become the place where your people already work, why isn’t it being used as your primary phone system? And what does this adoption gap mean for your voice roadmap in the years ahead?
This blog explores the seven key reasons behind low external calling adoption in Teams and what organizations can do to build a more effective, future-ready voice strategy.
Most organizations implement Teams to solve immediate collaboration needs. Chat and video meetings deliver quick, visible wins, and adoption grows organically.
Voice, however, requires:
Because of these complexities, voice often becomes a delayed phase of a larger rollout. The result is that the majority of users engage with Teams every day, but only a small subset ever make external calls on it.
Many businesses still rely on on-premises or hybrid PBX systems, particularly Avaya, Cisco, Mitel, and other established platforms. These systems have been in place for years and often support:
Replacing or integrating these systems is not trivial. In many cases, organizations maintain legacy telephony while Teams handles collaboration, creating parallel systems that slow adoption.
Business leaders are understandably cautious with phone systems. Voice is still critical for sales, customer service, and executive communication. Any disruption carries business risk.
Because Teams calling requires changes to routing, SBCs, carriers, and numbering, many IT teams take a conservative approach or postpone migrations altogether.
This caution can lead to an extended co-existence period where Teams is used daily but external calling stays on the legacy system.
Rolling out Teams calling in a single country is one thing. Doing it across 10, 20, or 50 countries introduces:
It’s not surprising that multinational deployments move slowly, leaving many regions on legacy telephony.
Even when Teams calling is deployed, users may not realize they can make external calls. In organizations with hybrid systems, employees might still default to:
Without clear communication, change management, and user education, adoption stalls and usage remains limited.
When Teams is used for collaboration but not voice, organizations often end up paying for:
This dual environment increases operational complexity and limits the benefits of consolidating communication into a single platform.
The fact that only around 6% of Microsoft Teams users make external calls isn’t a sign that Teams Voice is ineffective. It’s a sign that many organizations haven’t yet unlocked the full value of the platform.
A well-planned voice strategy can:
Teams has already become the digital workplace hub. Extending it to handle external calling is often the logical next step.
A global voice strategy needs the right expertise behind it, and Aura helps organizations unlock the full potential of Microsoft Teams by modernizing and simplifying their telephony environments. With deep experience in global Teams deployments, Aura enables businesses to consolidate legacy PBX systems and bring enterprise-grade calling directly into Teams. Through Aura’s Teams Phone solutions, organizations gain global PSTN coverage, number management, call flows, voicemail, auto-attendants, and centralized administration, all delivered through a cloud-first model.
Aura also helps navigate the regulatory and operational challenges that often slow adoption, ensuring secure SBC architectures, compliant routing, and uninterrupted service across multiple regions. With 24/7 monitoring, proactive support, and a proven track record in complex migrations, Aura provides the expertise needed to move from fragmented systems to a unified, modern voice platform. With Aura as a partner, businesses can increase adoption, reduce complexity, and build a future-ready communication foundation that fully realizes the value of Microsoft Teams.