The November 2023 Gartner Magic Quadrant for Unified Communications as a Service noted the following as a caution for Teams:

The addition of the Teams Phone Mobile along with pay-as-you-go calling plans and Operator Connect program for PSTN connectivity for Teams remains an area of uncertainty among organizations about which PSTN connectivity option is a best fit for their situation. Gartner clients often indicate that they are not clear about the Operator Connect offering, and how it differs from Direct Routing or Microsoft Calling Plans.

I think that’s a fair assessment, with Microsoft having recently rolled out a handful of new and expanded offerings there are plenty of options and they do have overlap and nuances. There are two main themes in this caution: how to connect “voice things” to Teams, and how calling plan licensing works. Let’s take those apart and see if we can clear up any confusion. I’ll also score things on categories of cost/billing, administration, technical complexity, coverage, and features.

Connecting Voice Things to Teams

There are five ways to connect “voice things” to Teams: Calling Plans, Operator Connect, Teams Phone Mobile, Direct Routing, and SIP gateway.

Operator Connect

Let’s start with Operator Connect, or OC for short. With OC, telcos partner with Microsoft to plumb their services directly in to Teams. You can review the list of telcos that can provide various services to various countries. There are a few global players, many regionals, and some national. You contract directly with these telcos for service, and they bill you directly. OC telcos set their own billing plans and rates.

Since OC telcos are plumbed directly in to Teams there’s no equipment to own or manage and thus no configuration time for that equipment. Your phone numbers are available to manage in TAC or via PowerShell, and each telco will offer a portal with varying levels of functionality. When you’re selecting a telco for OC, it’s worth asking about their portal features and getting a demo, especially around features like obtaining new numbers and configuring emergency addresses.

Calling Plans

Calling Plans, or CP for short, can be thought of as “OC by Microsoft”. Microsoft is your telco in this case, which means fewer relationships and bills to deal with. CP is also the fastest to set up, as you can acquire CP licenses in the same fashion as any other Microsoft license. You can be making and receiving calls within minutes. Number management is fully baked into Teams, and indeed it’s sometimes a challenge to understand what is a “Teams” thing and what is a “telco” thing – not that you have to, though. This easy-to-use management is excellent for “accidental administrators” in smaller organizations.

Microsoft has a number of different billing/licensing options for CP. Service is available in a number of countries, but OC from other telcos has the edge here.

Teams Phone Mobile

Teams Phone Mobile isn’t to be confused with the Teams app running on a mobile device. Teams Phone Mobile is a niche subset of OC provided by mobile carriers. Here, your mobile phone number is also your Teams number. For company owned devices this can save complexity and cost. For users who are always (or often) on the go and who are probably tempted to use their native mobile phone carrier for business anyway (*cough* sales guys *cough*) this simplifies things greatly for them, and prevents customer confusion since they no longer have two numbers.

This is a poor option for BYOD devices, that’s be left to “mobile carrier is personal, Teams app is work”. Availability is growing, however you may be limited to choice of mobile carriers.

Direct Routing

When it was being developed, Direct Routing (“DR”) was called “bring your own carrier” or “bring your own trunk”, which is still a great marketing tag line. With DR you connect a Session Border Controller (“SBC”) appliance to Teams, and then you connect anything you want to the SBC. This gives you monstrous amounts of flexibility that CP and OC can’t touch, at the cost of additional complexity and hardware. DR is how you integrate Teams with existing PBXs, other on-prem systems like paging, elevator phones and the like, basic SIP devices, as well as analog devices that you still have kicking around. You are responsible for providing your own carrier services to connect to the SBC, which means you can provide PSTN services to Teams anywhere in the world.

There are plenty of options for SBCs that work with Teams. They can be physical appliances, VMs, or cloud native services. They can be on-prem, in your data center, in a VM in Azure, Azure appliances, or owned/administrated/hosted by your carrier as part of your service – “SBC as a Service”. SBCs can come in high-availability pairs or clusters, and you can (should!) configure primary and backup units.

Owning and operating your own SBCs is not straight forward. There are different enough that any Microsoft or network technical staff will have a tough time properly configuring them. Partners are your friend here. You can also take advantage of SBCaaS with your telco, though you’ll lose much of the advanced functionality that makes the DR solution so attractive in the first place.

Direct Routing is also a requirement to take advantage of the Survivable Branch Appliance (“SBA”). The SBA can provide basic survivable telephony to a location should there be a network connectivity or Teams outage.

SIP Gateway

When an organization selects CP or OC for PSTN services, they’re left with a missing piece of the puzzle if they have analog or SIP devices that need to be connected. This could be paging systems or blue-light emergency phones, or the organization may have a number of existing analog or SIP phones that they don’t yet want to abandon. The only solution used to be deployment of an SBC, and then Microsoft introduced the SIP Gateway. The SIP Gateway lets you connect these SIP and analog (through an ATA or gateway, an “analog to SIP adaptor”) to Teams. This is only for voice endpoints, so you can’t add analog lines from a telco or do faxing.

SIP Gateway is an excellent choice for things like paging or those blue light phones. Some organizations that have a number of existing SIP phones that they don’t want to replace for financial reasons should carefully consider the total cost of doing so. Re-using existing SIP devices (which can include certain Cisco models as well as a number of other generic SIP phones) has a high administration cost as these devices cannot be managed through Teams the same as a Teams native phone. Each phone will need to be visited for a firmware change and registration to the SIP gateway. There’s a labor cost there, possibly a firmware/license cost for each device, and overall lower functionality for call functions, including dynamic e911.

Mix and Match

You’ve probably picked up from some of the above points that it’s possible to run a mix of all of the above options. This provides you with excellent flexibility and ability. Some common mix and match scenarios might be Direct Routing in the US with a handful of staff in the UK on calling plans. Or you may have Operator Connect everywhere but India, and select Direct Routing there to ease compliance with telecom regulations. Direct Routing is a requirement to take advantage of the SBA, however other locations – and even other users at the SBA location who don’t need the survivability – can be on other solutions.

I’ve also seen an organization deploy Direct Routing while they do a long-term migration from their existing PBXs while keeping full interoperability in place between the two systems. Once the migration is complete and the PBXs retired, they can strategically move some or all users to CP or OC services.

Voice Thing Licensing

When you’re licensing Teams for voice, there are two considerations. The first is that you need “Teams Phone System” for your users (or the equivalent license for shared phones). This is included in E5 licensing, otherwise “Teams Phone System” is available as an extra license to light up E3/E1 and F-license users. Devices that aren’t associated with a user get a “shared device license” – use this for common area phones, or paging gateways connected via SIP Gateway.

The second part is the PSTN access or “dial tone”. With OC, DR, and Teams Phone Mobile you obtain these services from your telco. For Calling Plans, you obtain those licenses from Microsoft. There are a couple of options:

• Domestic Calling Plan,
• Domestic and International Calling Plan,
• Pay-as-you-go Calling Plan,
• Communication Credits.

Domestic call plan gets a number of minutes per user per month. The quantity of minutes can vary per country, and some countries have a couple of different options. Typically this is something like 3000 minutes. These minutes are pooled between all users with the identical plan, in the same country.

Domestic and International Calling Plan combines your domestic minutes with international minutes, typically something like 600. Pooling rules apply here, too.

Pay-as-you-go is a base license per user per month with no minutes associated, and any minutes are billed against Communication Credits (see the next item below) or you’re on the New Commerce Experience in your M365 tenant, this is billed after the fact. This is a great option for users who rarely call, and when your overall minute pool is large enough you wouldn’t be able to make use of any minutes if you were to assign a domestic calling plan.

Communication Credits are a pre-paid credit. You can allow your users to use these credits to dial internationally when they only have a domestic calling plan, to place calls when minute pools have expired, or to place calls as a pay-as-you-go user. Communication Credits are typically tied to a credit card and automatically reload to your specified amount when they expire. Communication credits are also used for things like inbound calls to your toll-free numbers, and to dial out from Teams meetings if you’ve permitted your users to do that.

Your best course of action to decide which license to use is to pull date from your existing system. If you can’t do that, there is excellent reporting available in Teams where you can track usage. If you’ve got a pile of minutes left at the end of each month you may be able to bump some (or all) users down to pay-as-you-go. If you’re running out of minutes and burning into communication credits, you may decide to bump heavy minute users up to domestic or domestic and international calling plans. If you’re doing a phased rollout of Teams, keep an eye on this report to establish what adjustments you should make to your license purchases for future users.

The Scorecard

I promised a scorecard for comparison of the various options, so here it is, emoji style:

	Calling Plans	Operator Connect	Teams Phone Mobile	Direct Routing
Cost	😑	😑	😑	😑
Billing – combined with Microsoft or additional to a different organization	😊	😒	😒	😒
Administration effort	😊	😑	😑	😒
Technical complexity	😊	😊	😊	😒
Coverage (countries with service)	😑	😊	😑	😊
Features/Capabilities	😑	😑	😑	😊

Scorecard notes:

Cost comparisons between the various solutions is far too complex to give a “this one!” answer. License/user/number count, provider contract terms, and your negotiation skills will all factor into this. Make sure you consider the cost of things like SBC upkeep if you’re comparing something against Direct Routing.

Billing – this is a yes/no, with Calling Plans winning because it’s just an additional Microsoft license on your existing bill.

Administration effort – Calling Plans wins here because everything is so tightly integrated. OC is a close second place, but may not be so close if your operator decides to make things complicated for you in their portal or for things like obtaining new numbers.

Technical complexity – DR is the loser here with SBCs and their upkeep, and a more complex Teams configuration. This all goes away with CP and OC

Coverage is an ever-changing factor. CP have the least global coverage. OC leverages many telcos existing networks, where Direct Routing lets you hook anything up, anywhere.

Features/capabilities – This isn’t calling features like call forward or transfer. Rather it’s things like your ability to control who can call internationally, or to further restrict who can call *where* internationally.

Still have questions? Give me a shout in the comments!