The real cost of "we already have Teams."

The pitch usually arrives from inside the building, not from a vendor. Finance sees the Microsoft 365 spend, sees a separate five-figure UCaaS invoice, and concludes the two overlap. The instinct is reasonable and the savings look real on a napkin. The structural fact that the napkin misses is that "calling in Teams" is not one line you already own. It is three or four lines, most of which are not on the Microsoft 365 bill today, plus a compliance obligation that moves onto your desk the moment the incumbent leaves. The buyer who prices the whole stack makes a good decision either way. The buyer who prices the napkin signs up for a migration that lands close to what they were already paying.

Teams Phone is a separate add-on, not a feature of your Microsoft 365 seat.

Calling is licensed on top of Microsoft 365, not inside it. Microsoft's own admin documentation states plainly that "Teams Phone requires a separate add-on license" and that "for Teams Phone only, buy a Teams Phone Standard license." Most Microsoft 365 plans give your users peer-to-peer VoIP inside the tenant, which is why a quick internal test call succeeds and convinces everyone the capability is already there. External calling is the part that carries a license, and on E1 and E3 seats that license is not included. The practical read for a buyer is that the first line of any Teams calling quote is a per-user add-on you are not paying for yet, regardless of how complete your Microsoft 365 subscription feels.

A Teams Phone license still cannot place an outside call on its own.

The license buys the PBX; it does not buy the line to the phone network. Microsoft is unambiguous here: "in order to use PSTN telephony services with Teams Phone, the user account must be licensed with the Teams Phone application and also be equipped with a PSTN solution from your PSTN service provider of choice." That second requirement is a distinct commercial decision with four shapes. Microsoft Calling Plan makes Microsoft your carrier and meters minutes as its own license. Operator Connect lets a participating carrier keep the PSTN relationship while you manage numbers in Teams. Teams Phone Mobile turns a carrier SIM number into the Teams number. Direct Routing connects a Session Border Controller you procure and run. Each of the four still sits on top of a Teams Phone license, so no path collapses the stack back down to a single line.

The three-line stack is where "free with Microsoft" quietly becomes UCaaS-priced.

Stack the pieces and the economics stop looking like a rounding error. A calling seat is the base Microsoft 365 subscription, plus the Teams Phone Standard add-on, plus a PSTN connectivity option, plus outbound minutes or Communication Credits where the model meters them. There is a licensing wrinkle that raises the base as well: since April 1, 2024, new enterprise customers buy Teams as its own SKU alongside a Microsoft 365 suite that no longer includes it, so the "we already have it" seat is itself two purchases before calling enters the picture. None of this makes Teams Phone expensive in the abstract. It makes the comparison honest. When each line is on the table next to the incumbent's all-in per-seat, the migration is evaluated as a like-for-like swap rather than as free capability hiding inside a bill you already pay.

What breaks: the E911 obligation you inherit, and the contact center you do not get.

The two things most likely to surface after signing are emergency calling and queue routing, and both are structural rather than product defects. On emergency calling, Kari's Law and the RAY BAUM'S Act require a multi-line phone system to dial 911 without a prefix, notify designated staff, and deliver a dispatchable location, not just a street address. Teams can satisfy this, but Microsoft's documentation puts the configuration on the administrator: emergency calling policies, dynamic location lookup, and a Location Information Service have to be set up, and Microsoft notes that Teams desk phones "do not support the work-from-home experience," which is exactly the remote-seat case that trips compliance. When you leave a managed UCaaS provider that handled 911 provisioning as part of the service, that work becomes an internal project. On the contact center, Teams Phone delivers auto attendants and call queues, not agent supervision, skills routing, or full reporting. Organizations that need those add a certified Connected Contact Center for Teams or the Queues app on Teams Premium, which is another licensed layer to price rather than a feature you inherit.

The decision a competent operator faces is narrow and answerable: is Teams Phone genuinely cheaper than renewing our UCaaS, or does it only look cheaper because most of its cost is not on today's Microsoft bill? The answer comes from pricing the whole stack, not the base seat. The seven lines below are the true-cost worksheet we run at the front of every Teams-versus-UCaaS conversation. It is vendor-neutral and built to surface the costs the napkin hides. Paste it into your evaluation.

The worksheet is not an argument against Teams Phone. For an organization already standardized on Microsoft 365, with simple call flows and no contact center, the stack can come out ahead, and it consolidates vendors in a way that has its own value. The point is to make every line visible before the redline conversation, so the choice is made against a full number rather than against the assumption that calling is already paid for. The renewal-side version of this same problem, where an incumbent's number drifts up between contracts, is covered in the UCaaS renewal trap, and the question of which AI is already bundled in either platform is in what your UCaaS already ships with.

Why this is structural, not a knock on Microsoft.

The gap between "we have Teams" and "we have telephony" is a packaging artifact that shows up for every buyer the same way, because Microsoft sells collaboration and calling as separate goods on purpose. Teams is in the seat. Teams Phone, PSTN connectivity, and the contact-center layer each carry a real cost to serve, so each is licensed on its own. The exact suite names and the exact add-on prices will keep changing, and the April 2024 SKU split shows they already have. The dynamic does not change. Anchor the evaluation to the full stack a calling seat requires, and the choice between Teams Phone and a standalone UCaaS becomes a clean comparison instead of a story about capability you think you already bought.

How Cardinal prices a Teams Phone migration.

When a client weighs Teams Phone against a UCaaS renewal, we build the seven-line stack for their actual seat mix, benchmark each line against the market so no piece is priced on the vendor's first quote, and put the all-in number next to the incumbent's all-in number. Then the E911 and contact-center work is scoped as real project cost rather than left as an assumption. The output is a like-for-like figure, so the decision to switch or stay rests on the total, not on the base seat.

See the Cardinal Method →  ·  See the supplier pool →  ·  UCaaS vendor selection →