How To Make an External Call With Microsoft Teams

How to make a call in Microsoft Teams

And How To Make It Way Easier

According to a Forrester research report, unified communications and collaboration with Microsoft Teams can give a “pay-back” in just six months. But to create a truly unified platform, you need to unite both internal and external collaboration within Teams. External collaboration (and phone calls specifically) remain a glaring weakness in most business collaboration tools. The regularity with which people need to pick up a phone and make a call is so common that we don’t even notice: calls are still important. So, what’s the answer? How do you place an external call with Microsoft Teams?  

You have four options, and this article will walk you through the pros and cons of each, and then explain how to best set up telephony as part of your complete business collaboration platform — rather than an add-on or after-thought.

Option 1: Add external users as guests

Within Teams, you can add external users as guests and call them using teams-to-teams calling capabilities just like you would to reach internal users. Guest settings can help you collaborate with regular external stakeholders or contributors. However, it doesn’t really work for less structured communication. 

Sales teams, field teams, or any other individual who routinely needs to communicate with people outside of your organisation will need a better solution. 


  • Guest access is a standard capability with your Teams licence. 
  • It’s relatively simple for users, once set up.
  • Guest access is good for regular communication.


  • Setup requires manual input and can be administratively challenging to maintain — who validates, adds and deletes guests?
  • Potential security issues — who monitors and controls who has access to your account? 
  • External users need to have an existing Microsoft 365 work or school account. If they do not have one, they will be directed to create a free account. In all cases, they will need to create a Teams account and know how to use the interface. 

Option 2: Use cross-launch overlays

Applications like RingCentral and Zoom (among others) all enable external calling with specific plans. Some of these apps provide software overlays to quick-launch their products from Teams. 

These applications allow you to place external calls. However, you aren’t really placing them from Teams, you are just cross-launching a different application. Although this is a functional solution, it’s not integrated and that brings a lot of disadvantages. 


At first glance, this is a simple short-cut to providing external call capabilities with Teams. 

  • There are no additional fees levied by Microsoft.
  • If you already have one of these other calling apps, you can make it slightly more convenient to access with Teams.
  • It’s a fast way to “get the job done”. 

The problem is that it actually isn’t getting the job done.


Additional apps are not integrated and don’t solve the problem of not being able to place a call with Teams. 

  • Incoming calls won’t ring the Microsoft Teams client, they will ring the third-party app. 
  • These solutions can also be relatively expensive. However, prices will vary significantly depending on the specific third-party application.

The outcome is: 

  • Multiple access points: Without the ability to place an external call with Teams, users need to sign into multiple devices and systems.
  • Hardware duplication: You may have to invest in unnecessary user devices and infrastructure.
  • Decentralised information: Call records, contacts, message histories and more become harder to find and end up stored across different applications. 
  • Inconsistent workflows: Having to switch between devices and interfaces creates challenges for training, onboarding and support. It’s also just inefficient. 
  • No federated presence: Using multiple applications prevents users from centrally updating their status and benefiting from presence notifications across all devices and communication channels. 

Option 3: Microsoft Phone System and Calling Plan

The ultimate goal should be to make Teams your only business collaboration tool. That means integrated external calling — and the gateway to that outcome is Microsoft Phone System. 

Phone System is Microsoft’s answer to a PBX (Private Branch Exchange). It provides call management and control functionality. It’s included as part of Microsoft/Office 365 E5 but otherwise needs to be purchased as an add-on. The diagram below illustrates the add-on licences required to enable external calling based on the Microsoft or Office 365 package your business holds. 

For a full rundown of purchasing options and Phone System capabilities, check out our blog — Microsoft Phone System Reviewed. 

Microsoft Teams Calling - License Diagram

However, Phone System doesn’t provide external call capabilities on its own. For that, you need to add one of two additional options: 

  • Microsoft Calling Plan (domestic or domestic and international).
  • A third-party integration (we’ll come on that in Option 4).

What is Microsoft Calling Plan?

Microsoft Calling Plan is the Microsoft-provided option for placing standard phone calls with Teams. You need a Phone System licence to activate Calling Plan. However, depending on your other Microsoft licences, you may be able to bundle this purchase. 


Phone System with Calling Plan is a good solution for your business if:

  • Calling Plan is available in your region — there are restrictions.
  • You want to keep your solution fully hosted by Microsoft.
  • You don’t have particularly sophisticated calling requirements. 


Calling Plan’s limited regional availability can be a problem. However, there are a number of issues you will encounter no matter where you are located.  

  • Pricing is complicated and expensive: The total additional cost will depend on your existing licences and geography, and you will need to look into the specifics. You also need to get both Calling Plan and Phone System. But particularly compared to some Direct Routing options (see Option 4), Calling Plan is the more expensive choice — with per-user pricing and multiple licencing requirements.   
  • There are handset compatibility issues: Using Phone System and Calling Plan, you are limited to the endpoints and handsets supported by Microsoft. This can lead to additional hardware investments and an inability to use your preferred devices.  
  • Phone System isn’t a real PBX: The fundamental issue with Calling Plan is that it relies on Phone System as your control and reporting tool. Compared to a standard telephony solution, Phone System leaves a lot to be desired. For example, there is no call recording or user-specific reporting or controls. And the call queue management capabilities simply aren’t suited for high-volume environments. 

Fundamentally, Calling Plan is let down by Phone System — which cannot truly replicate the functionality of a real corporate telephony system. Calling Plan and Phone System will allow you to place external calls with Teams, but it’s unlikely to allow you to replace your existing phone system with Teams. This kind of defeats the point of unified communication, and it can be more expensive than more sophisticated, Direct Routing options.    

Option 4: Direct Routing with Teams

A Phone System licence also opens the door to “Direct Routing”. This option connects Teams to a standard PSTN (Public Switched Telephone Network) carrier, merging Teams with a traditional telephony network. With this option, Phone System effectively becomes a prerequisite licence, and is replaced by a real PBX in terms of functionally. 

Direct Routing is a truly unified solution. Not only will this option enable you to place external calls from Teams, it allows Teams to become the central hub of your entire telephone system. With Direct Routing, you can: 

  • Deliver a fully functional telephony system straight out of Teams. 
  • Unify your communication and collaboration infrastructure. 
  • Transform Teams into a complete business collaboration platform. 

Full disclosure, we, Callroute, provide a Direct Routing solution. We can’t provide details on every product on the market, but we can use Callroute’s functionality to explain the advantages of placing a phone call with Direct Routing.

  • Instant integration: Callroute has auto configured the integration process. That means that we can get you set-up to call from Teams in minutes (provided you have the right prerequisites), while most other Direct Routing providers can take up to seven days. We can also integrate any legacy equipment such as PBX’s within one central platform.
  • Flexible and affordable: We charge per-channel, rather than per-user. That means you pool your users across multiple phone lines so you pay for the capacity your business requires rather than every user. Auto scaling expands capacity as demand increases, so no one ever hears a busy tone. Compared to Microsoft Calling Plan in particular, this delivers a better outcome at less cost. 
  • Unified and complete: You are connecting Teams to a fully functional telecommunications network. You get the reporting, security and advanced calling features you need to unify communication, simplify infrastructure and optimise collaboration. Extensive research combined with our background in corporate telephony has enabled Callroute to be designed as a sophisticated solution capable of replacing existing phone systems. 
  • Global reach: Purchase area codes from a catalogue of over 10 million numbers, with simple international rates & global calling plans. Callroute enables global reach at affordable rates.
  • Managed service: Set-up and customer support are included in the Callroute service, with no hidden costs. We can also port numbers (including international numbers) if required.

To find out what Microsoft Licences you need to get started with Direct Routing, check out our simple guide.

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Creating a complete business collaboration platform

On its own, Microsoft Teams provides all of the channels you need for internal communication and collaboration — chat, video and audio calls, file sharing, company-wide announcements and personal messages. 

Where it falls down is enabling external communication. We believe what completes Teams is integration with real-world telephony. 

Callroute isn’t the only option on the market. But, if you want to unify all your communication and collaboration with Teams, we think it’s the best place to start. We offer businesses a free channel for life rather than a time limited trial, 250 minutes and 1 allocated UK number, no card required. Start making external calls from Teams in minutes.