Is Microsoft Teams capable of replacing your phone system?

, Jul 12, 2021

By Tim Wadey

“Our next phone system will be Microsoft Teams.”  I have heard this from several contacts over the last few months.  And it quite probably will be! But will it be that simple?

Increased use of Collaboration tools.

Lockdown saw an explosion of the use of collaboration tools, firstly to help teams collaborate, and once we had learned to collaborate within teams from our desktops and devices, the next natural step was using the same app for 1-to-1 calling.  Use grew in our personal lives too, “zoom quizzes”, family reunions, charity committees and famously, parish councils exploited the power of collaboration tools.  We also learned to use mature features to improve the calling experience – you naturally notice a colleague’s presence status and message “are you free for a call”, instead of interrupting with ring tone.

So given this great experience, this direction of travel seems quite natural.  It is also following the usage trajectory of collaboration tools across the lockdown period.  Whilst statistics are changing all the time and hard to quantify (users, minutes per month etc.), the four key platforms (Teams, Zoom, Slack and WebEx) showed usage growth of 10-40-fold over the last year.  It is paralleled by the many users who use applications like Facetime or WhatsApp to communicate with friends and family by voice and video calling aligned with messaging., it is no surprise we have seamlessly adopted similar technology in our working lives. When we want to work with people we know and have good network connectivity to modern devices we now naturally use a collaboration tool rather than making a phone call. 

Microsoft Teams compared to traditional telephony systems.

But there is a bigger picture - the telephony system is one of the world’s largest machines.  There are 5.27 billion unique smartphone users, 10.88 billion mobile connections (includes IoT etc) and 913 million fixed phone lines (down from a peak of 1.25 billion a decade ago). So, in round terms there are 11.8 billion end points that are connected by dialling an 11 – 15-digit number to provide a basic service.  And that same device can take calls from businesses contacting customers, reconnect long lost colleagues, and join conference calls, all in a consistent and deterministic way.  In contrast, Microsoft Teams is currently reporting 145 million regular users – just 1.2% of the number of phone endpoints globally.  Whilst this is a low percentage, it has grown from 13 million before the pandemic.  To become the platform of choice, Teams must be fully integrated with the public telephone network in a way that most organisations have yet to embrace.


The difference between collaboration and calling functionality is also becoming less distinct, but this highlights the different use cases and how differing options might change the user experience. Collaboration systems do not replace all the functionality of a corporate phone system (yet). The sort of functions that are currently under-developed in Teams include:

  • Contact Centre
  • Hunt Groups
  • Call forwards
  • Manager/secretary functionality
  • Unattended phones (Lobbies, lifts, conference rooms, lecture theatres etc.)
  • Analogue devices
  • Receptionist functionality

As with all software development, the manufacturer is busy adding functionality and every time I review the Microsoft site these issues are being addressed.  Reception functionality is being delivered through an “auto-attendant”, and call queues, call forwarding, group pickup and call transfer are just some of the features that that are now incorporated in the Microsoft Phone System product, now addressing the key functional differences between collaboration systems (Teams) and a corporate private automatic branch exchange (PABX).


How they integrate with the public switched telephone network (PSTN) is also critical.  It requires full integration that delivers incoming calls to the correct device and allows outbound dialling to cost effectively connect to other phones, within an entitlement which can differ per user.  The Teams integration can currently directly connect using new numbers or your existing numbers (dial plan) can be migrated in, but then only gets the basic Teams functionality.  To get the fullest functionality available, you need to anchor the existing connection on a device known as a “Session Border Controller” (SBC) - such as Cisco CUBE.  This will allow for support of devices like analogue phones and modems, old fax machines and existing contact centres.  The SBC also integrates the existing telephony service provider with Teams and with any retained functionality of your existing solution.  There are of course new Microsoft Teams compatible third-party contact centres emerging as add-ons, but adopting this approach requires that the contact centre be refactored to new software.

Functionality vs cost saving.

The main driver is of course that Teams, in the way we use it today, seems to be free. It’s bundled in an overarching Enterprise Agreement, it costs nothing additional to use, there are no call charges.  As a replacement for the costly PABX and its external connectivity it would initially appear to be a good option.  But the Microsoft Phone System that gives most of the required functionality is not free - it comes with a monthly service charge per user or the need for a calling plan to pay for external calling despite the functionality being bundled in the E5 subscription.  The need to trade between the cost and complexity of retaining a Session Border Controller and some equipment or losing functionality needs careful consideration.  What at first seemed like an easy cost saving, needs expert input to ensure that the business retains its full ability to communicate as part of the global phone system.  As a Cisco Global Gold Partner, and one of the top 1% of Microsoft Partners globally, Logicalis is of course here with that advice if you choose this path.

As the workplace, in particular for knowledge workers, circles back to the office and adopts a hybrid or blended approach, collaboration tools will increasingly enable and enhance teamwork.  Reduced travel will increase productivity and drive the pace of business.  To enable this requires that the integration of the systems is as tight as possible – like the global Internet backbone or telephony systems.  Your collaboration tool strategy will only be part of your overall workplace transformation.

Get in touch with Logicalis to discuss your business goals. These should feed through to how technology works together to enable your business to give employees and customers the best experience possible.

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