How To Bring Your Own Carrier To Microsoft Teams (BYOC) 

How To Bring Your Own Carrier To Microsoft Teams (BYOC) 

If you’re worried about call costs spiraling out of control, have several PBX vendors to consolidate, or are working through a project to move everything into Microsoft Teams, the Bring Your Own Carrier (BYOC) option might just be what you’re looking for. 

If you have a PSTN calling provider other than Microsoft, it’s now more than possible to use them for your minutes while using Teams as the front-end interface to place the calls. 

In this blog post, we walk through the why, how, and how to right now of BYOC in Microsoft Teams. 

Why BYOC to Microsoft Teams? 

You’ve probably got enough reasons yourself.  

They might include: 

  • Pressure from procurement 
  • Pressure from IT 
  • Long legacy PBX contracts 
  • Geographical areas unsupported by Microsoft 
  • A wider digital transformation program 

But, if not, and the decision is down to you, consider bringing your own carrier to use as your calling provider inside Teams for these reasons: 

  • Potential cost savings: paying retail or creating workarounds is never cost-effective. 
  • Flexibility per site: scale as and when you need to. 
  • Control per site: total access and visibility of calls and costs. 
  • Simple number management: make changes on the fly. 
  • Emergency services access: simple and compliant configuration. 
  • Lack of feature parity: while Teams Phone enables many PBX features, complex requirements have yet to been catered to entirely. 
  • Redundancy: what if Teams goes down? A solid disaster recovery plan must include multiple platforms for making and receiving calls. 
  • Integration options: like contact center and CRM. 

It all begins to add up, doesn’t it? It’s easy to see why BYOC for Microsoft Teams is not just a blue-sky requirement, but almost a must-have for the modern communications stack. 

Isn’t native Teams Calling easier? 

The answer is “Yes, if”.  

That depends on several things: 

  • You need to activate new users quickly 
  • You only have very basic calling requirements 
  • You don’t plan to scale to a larger number of users 
  • You don’t have multiple regions (that are unsupported by Microsoft) 

It’s possible to port your existing numbers to Microsoft. Microsoft is now a genuine telecoms provider, so the process is the same as porting to AT&T or BT. 

Businesses love Calling Plan if they plan to only make small changes via the Teams Admin Center and want to consolidate their (fairly small) calling infrastructure under one roof. 

But, when you need advanced features, technical changes, and global scaling, Calling Plan becomes either expensive or impossible. 

Isn’t native Teams Calling cheaper? 

You’d think so, wouldn’t you? 

With everything Microsoft, it makes sense that you benefit from cost savings. But there’s a lot of instances where you’re going to be paying for Calling Plans that go unused. 

Think about it… 

You license every user with Teams Phone and Calling Plan. That costs $20 per user per month. If you have 2,000 users, that’s $480,000 per year.  

Now think about this… 

How many of those users actually make anywhere near the number of calls they get minutes for? 

In fact, how many make any external calls at all? 

Research by Nermertes indicates between 50% and 75% of available minutes get used by Calling Plan customers, leaving unused minutes and creating a chasm between cost and value. 

When deploying Teams Phone at scale, 50% of 2,000 users, for example, is a large cost gap that looks extremely unappealing on financial reports. Especially, when there’s a more cost-effective alternative. 

Which carriers integrate with Microsoft Teams? 

It’s impossible to document the full list of calling carriers that integrate with Microsoft Teams, due to the sheer number and ever-increasing list. 

Thanks to Microsoft initiatives like Direct Routing and Operator Connect, almost any calling provider can integrate with Teams. Thus, it’s very possible to bring your own carrier to Teams. 

As of the end of November 2023, there are 78 Operator Connect partners. 

BYOC options for Microsoft Teams 

You have four main options if you want to bring your own carrier to Microsoft Teams: 

  1. Use a Microsoft App Store integration 
  1. Direct Routing  
  1. Operator Connect 
  1. Callroute 

Microsoft App Store integration 

If you’re a cloud PBX customer of Zoom, Webex, or any of the major VoIP players, you could have a pre-built calling integration in the Microsoft App Store. By using cloud to cloud APIs and leveraging Microsoft’s open ecosystem, we now see a lot of collaboration crossover in Teams. 

In the image below, you can see the Zoom Phone dialer, history, and voicemail gets embedded into your Teams client. 

Zoom example of Bring Your Own Carrier (BYOC) to Microsoft Teams

To enable this, you must have a relevant Zoom Phone license, enabled for external calling, and the config file to upload to Teams. 

The same process and prerequisites apply to the majority of major VoIP and cloud unified comms players. 

The benefits here are that you can use your existing cloud call carrier within Teams. However, it’s not providing native dialing. In some cases, like contact center or mobile users, moving to a new app to make and receive calls is not an option. It adds extra clicks and switches, which aren’t conducive to productivity. 

The next few options provide a native calling option in Teams… 

Direct Routing 

Direct Routing is when Microsoft supports connecting session border controllers (SBCs) to Teams. This could either be your own SBC or a vendor’s environment.  

The physical or virtual SBC connects telephony (on-premises or virtual) on one side to the cloud (Teams). There’s no certification for vendors or end customers to become ready-to-use for Teams. Only the physical equipment can be Teams-certified.  

When you opt for Direct Routing, you get Teams access to unique functionality that an SBC enables. This includes traditional PBX features that you can’t (yet, at least) replicate on a Microsoft Calling Plan deployment. 

Microsoft Teams Direct Routing is an example of BYOC

From a customer point of view, research by Nemertes suggests that the average per user per month spend on PSTN access is $7.91. This represents a significant cost saving compared to $20 per user per month for Teams Calling. 

Operator Connect 

Operator Connect is when carriers are approved by Microsoft to provide direct cloud calling access via Microsoft Teams. Instead of using Microsoft as the calling provider, you use an approved operator.  

This does mean, however, your calling carrier must be an approved Operator Connect partner. Unlike Direct Routing, you can’t just get set up with an SBC. 

For example, in the UK, you might have an existing calling agreement with BT. In the US, it might be Verizon or AT&T. These are all approved Operator Connect partners who can provide cloud telephony via Microsoft Teams.  

When set up, users make calls using their Teams client, but the “Operator” makes the call behind the scenes. Just like Direct Routing, there’s no difference seen by users making calls. 

Operator Connect is one way to bring your own carrier to Microsoft Teams

How to choose which Microsoft Teams BYOC option you need 

Both Direct Routing and Operator Connect provide substantial options if you use Teams for meetings and collaboration and want to move your telephony and calling to Teams too.  

Here is an overview of the differences between the two main BYOC options if you need to achieve native PSTN calling in Teams: 

Microsoft Teams Direct Routing  Microsoft Operator Connect  
Bring your own carrier  Choose from approved carriers  
On-premises or cloud managed SBC Cloud only  
Session border controllers must be approved  Operators must be verified by Microsoft  
Managed, indirect connection between carrier and Microsoft  Direct connection between carrier network and Microsoft  
Numbers managed on third-party software Numbers managed in Teams Admin Center  
Different interface per SBC Same interface if you have multiple carriers  
Available wherever your SBC is  Not available in all countries  
Third-party SBC SLA Microsoft SLA  
Support for legacy PBX functionality via SBC Legacy PBX functionality not supported  
Supports all PBX integrations  Supports Microsoft 365 approved integrations  
Supports hybrid deployments  No support for hybrid deployments  
Configurable voice routing  Standard voice routing only 

There are various pros and cons that change per business, and you should pay attention to this when making a decision.  

What’s not made easy with either solution is catering to multiple calling providers and multiple locations.  

For example, you might have your New York office running Teams for collaboration and AT&T for telephony, but your London office is using Teams plus BT.  

From an admin perspective, the desired state is that you connect your carriers, contact centers and your PBX users together in one place.  

What you need is a single platform that can connect any carrier, in any country to Microsoft Teams.  

Which is exactly what Callroute does…  

We put number management, policy management, and PSTN connections into a single portal.  

Bring your own carrier to Microsoft Teams without the hassle 

If you don’t want the hassle of buying new hardware or calling services, you could connect your existing carrier and services to Teams with our cloud integration. 

There are two deployment models you can choose from: 

  1. Side-by-side  
  1. Upstream cloud 


Our side-by-side deployment model gives you the lowest barrier to Teams Phone integration on the market.  

All you need to do is make a small change to your existing voice gateway to connect to Callroute, and that’s it. 

Callroute topology diagram for Microsoft Teams BYOC

The side-by-side model allows you to quickly deploy your Teams Phone proof of concept without making huge changes to your existing calling solution. You don’t need to inform your carrier, modify your PBX, or commit to new product contracts. 

Using Callroute side-by-side offers you the flexibility of beginning your Teams Phone journey from as little as one user on a 30-day contract and provides you with a Teams Phone certified calling solution with no hardware. 

Upstream cloud 

Our upstream cloud model is the perfect solution for you if you’ve decided to integrate Teams Phone in your business permanently.  

In this deployment model, you connect your existing carrier(s) to the Callroute cloud directly then connect Teams and your other phone systems to Callroute. 

Upstream cloud diagram for Microsoft Teams Bring Your Own Carrier (BYOC)

Once your carriers are connected to Callroute, you can decide where calls should be routed to based on the called number. You can route individual numbers to specific phone systems giving you complete control over your calling services. 

When connecting all your phone systems to Callroute, you benefit from cloud on-net calling between systems. This means that users using one phone system, e.g. Cisco CUCM, can call other users within your business who use Teams Phone without routing calls to your carrier. 

Connecting all your carriers to Callroute also removes the need to port your numbers or arrange a service migration with your carriers when you want to move users to Teams. This gives you the flexibility to make routing decisions quickly and without red tape or additional cost. 

The biggest benefit of using Callroute for your calling connectivity is that you can add and remove your phone systems at your own pace. When you add a new system, this system becomes instantly available within your Callroute cloud and connectivity to your carriers and other phone systems is instantaneous.  

This flexibility to add and remove carriers and phone systems based on your needs is unrivalled within the telecoms industry. 

Whichever deployment model you choose you can easily change at any point in time. 

Instead of milling around making countless changes and forever calling your supplier, you could connect your voice services to Microsoft Teams within minutes with our one-click integration.   

There are no infrastructure or deep technical skills required. Just access to our self-service platform.  

Inside the portal, you can:  

  • Automatically assign Direct Routing phone numbers  
  • Automatically assign Microsoft Calling Plans phone numbers  
  • Automatically assign Operator Connect phone numbers   
  • Mix and match locations, users, and numbers  

You also benefit from our auto-provisioning service, which helps you save time and money on new user assignments, moves, adds, and changes.  

There’s no more lengthy setup and there’s no human to make human error. You just create a user persona template and leave the rest to our automation.  

Microsoft Teams auto provisioning

Sounds like something you want to explore?  

👉 Find out more about Callroute’s Teams Calling integration here 🔥 

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Intermittent Microsoft Teams calling issues reported globally. This issue appears to be affecting all Microsoft customers worldwide. Microsoft are currently investigating the issue. All Callroute systems are fully operational. More information will be provided as soon as possible.