Why Are You Paying for Two Phone Systems?
- Read Time: 6 mins
If your organization is on Microsoft E5 (or A5 or G5), you already own a phone system. It’s called Teams Phone, it’s included in your license, and there’s a good chance you’re not using it.
It’s one of the more common gaps in many Microsoft deployments. Organizations upgrade to E5 for the security features, the compliance tools, the advanced analytics. The voice capabilities come along for the ride, but nobody turns them on. Meanwhile, the existing phone system keeps getting renewed.
For organizations on E3 or other M365 plans, Teams Phone is a straightforward add-on that changes the consolidation math. But for E5 customers, the conversation is different: you’re not evaluating whether to buy something new. You’re deciding whether to use something you’re already paying for.
This article covers what Teams Phone actually does, why Microsoft shops in particular tend to find it a natural fit, and what getting there looks like in practice.
What Unified Communications Actually Means (and Why Most Companies Don’t Have It)
Unified communications is this simple idea: one platform for voice, video, chat and collaboration. Not four tools that mostly talk to each other. One.
Most Microsoft shops are closer to that than they realize. Teams handles meetings. Teams handles chat. Teams handles file sharing, presence and project collaboration. The gap—almost universally—is voice. Calls still route through a separate system, managed in a separate admin console, supported by a separate vendor.
That separation made sense at some point. A VoIP system got deployed when Teams was a meeting tool. A PBX contract got renewed before anyone mapped it against the E5 roadmap. The Microsoft investment grew, but the phone system didn’t follow.
So most orgs get a communication environment that’s almost unified. And for E5 customers specifically, it’s one where the solution is already licensed and waiting.
What Microsoft Teams Phone Can Do
Teams Phone is a cloud-based phone system built directly into Microsoft Teams. It replaces the need for a separate PBX or standalone VoIP platform by bringing inbound and outbound calling into the same interface your team already uses for meetings and chat.
For organizations on Microsoft E5, A5 or G5, Teams Phone is already part of the license. There’s no additional purchase required — just the configuration and connectivity setup to activate it. For organizations on other M365 plans, Teams Phone Standard is a per-user add-on that still meaningfully changes the consolidation picture.
It works on any device running Teams. A desk phone at a workstation. A softphone on a laptop. A mobile app in the field. The experience is consistent and management lives in one place: the Teams Admin Center.
On the connectivity side, there are three ways to connect to the public telephone network:
- Calling Plans are Microsoft-managed. Microsoft handles the carrier relationship and you add phone numbers directly through Microsoft 365. The cleanest all-cloud setup for organizations that want to simplify.
- Direct Routing lets you bring your own TELCO. If you have an existing carrier relationship you’d like to keep, Direct Routing makes that possible without abandoning what’s already working.
- Operator Connect is a middle path: a certified third-party carrier connects to Teams through the Admin Center, so you get carrier flexibility without managing your own session border controller.
Beyond calls, Teams Phone adds capabilities standalone VoIP systems typically don’t offer. Voicemail transcription. Call summaries. Integration with Microsoft 365 Copilot for AI-assisted call intelligence. SMS messaging through Teams for teams that communicate with customers across channels.
One thing worth understanding for Microsoft shops specifically: Teams Phone is not a closed system. A broad range of third-party applications tie into it directly—contact center platforms, compliance recording solutions, operator connectivity services and more. Choosing Teams Phone means those tools run on top of a voice infrastructure that’s already integrated with the rest of your Microsoft environment.
Microsoft was named a Leader in the Gartner Magic Quadrant for Unified Communications as a Service for the seventh consecutive year in 2025. Microsoft has shown sustained platform investment, and they have been recognized for it.
On E3 and evaluating an upgrade to E5?
Teams Phone being included in E5 is one piece of a broader value story. E5 also adds Microsoft Purview for compliance and information protection, Microsoft Defender for advanced security, and Microsoft 365 Copilot capabilities that extend across Teams, Outlook and the rest of the stack.When you add those up against a standalone Teams Phone add-on plus whatever security and compliance tools you’re currently running separately, the per-seat cost of moving to E5 often looks different than it does as a simple line-item comparison.
If you’re evaluating the upgrade, it’s worth mapping your current tool spend against what E5 includes before making the decision. HBS can help with that conversation.
The Real Cost of Not Leveraging Microsoft Teams Phone
For E5 customers, the cost question has a clear answer: Teams Phone is already in the license. Every month that a separate phone system runs alongside it is a month of pure redundancy spending.
For organizations on other M365 plans, the math is different but the direction is the same. Running two communication systems means two admin consoles, two support contracts and two separate hardware lifecycles. It means your IT team carries overhead for a phone system that exists entirely outside the environment they manage every other day. When something breaks, there’s another vendor to call.
There’s also a user experience cost that doesn’t appear on any invoice. Every time an employee leaves Teams to make a call, they break their workflow. They lose conversation context. They come back to a different window. It’s a small friction that compounds across an organization.
And there’s an AI cost. Microsoft 365 Copilot’s call intelligence features (transcription, summaries, suggested follow-up actions) only function when calling lives inside Teams. Organizations running a separate phone system are paying for an AI layer that can’t do its full job.
Teams Phone Migration
Most organizations that reach this conversation are further along than they think. Moving to Teams Phone isn’t a rip-and-replace project, but a structured transition, and the right path depends on what you’re already running.
A good assessment starts with a few straightforward questions:
What’s your current call volume?
What’s in your existing PSTN contract, and when does it expire?
Do you have number porting requirements?
Are there specific call flows, auto-attendants or call queues that need to carry over?
Those answers shape the licensing recommendation and the rollout sequence.
On the licensing side, most M365 customers need the Teams Phone Standard add-on as a starting point. From there, the PSTN connectivity decision (Calling Plan, Direct Routing or Operator Connect) depends on whether you want to bring your carrier relationship, start fresh with Microsoft, or land somewhere in between.
On hardware, HBS works with several strong options depending on your environment. Yealink is one of our consistent preferences. Their desk phones, headsets and conference room systems are certified for Teams Phone, purpose-built for the Microsoft environment and reliable across deployments of every size.
For organizations that don’t need a physical phone at every station, a softphone through the Teams client paired with a Yealink headset handles most use cases cleanly. Poly, available through HP, is another solid option where it fits.
Rollout works best in phases. Start with one location or one department. Work through number porting, test call quality, train the users who’ll be most vocal about any issues. Then expand. A phased approach keeps risk contained and gives your team time to develop confidence in the deployment before it’s organization-wide.
One note on scope: this isn’t a project that should start with a vendor pitch. HBS starts with a discovery conversation about your current environment, your existing contracts and where you actually want to land. The discovery determines our recommendation.
One Less Piece of the Puzzle
For organizations already committed to the Microsoft stack, Teams Phone removes a piece of the puzzle rather than adding one. There’s no new platform to learn. No new vendor to manage. No parallel environment to maintain. Just voice—finally living in the same place as everything else.
For E5 customers, that’s a conversation about activation, not acquisition. For organizations on other M365 plans, it’s a consolidation conversation with a clear cost rationale. Either way, the path forward starts the same place: understanding the current environment, identifying what’s in the existing contracts and determining what a realistic transition looks like.
HBS works with organizations across the full process: the discovery conversation, the licensing fit, the hardware recommendations and the phased rollout. Many clients arrive already knowing Teams Phone is where they want to go. What they need is a structured path to get there without disrupting the business.
Ready to Evaluate Teams Phone?
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