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Further to our recent article around “what comes next”, we have been inundated with interesting conversations and projects about one product in particular – Microsoft Teams. 

What is clear is that many organisations have deployed MS Teams (Teams) to some extent within their business – either in advance of this pandemic or as a direct response to it.  Increasingly we see a clear picture that many ‘get it’ when it comes to the sharepoint side of things and integration with wider Microsoft stack – but when it comes to voice the level of understanding varies wildly. So here’s a quick overview, as I see it, of what the options are for enabling Teams, where it might be appropriate (or not appropriate!) to do so – the “art of the possible” if you will. Of course, I’ll take the liberty of referring to “our offerings” throughout – but that’s only right: CVD have a comprehensive skillset around Teams and should absolutely be considered as a potential partner for any organisation considering the deployment of Teams and associated works. 


As we all know, there is no one-size-fits-all approach for most things in life, and where Teams is concerned this also holds true. We believe that there is absolutely a “journey” for most organisations as they move towards Unified Communications (UC)(for a variety of reasons) – and that our role is to be an excellent and knowledgeable partner alongside our clients. We identify what the viable options are for our clients, highlight the benefits and disadvantages (alongside cost implications) and outline the process for design, implementation and support for any offering. 

I won’t dive into the “should I use Teams or something else” within this conversation – that’s a topic in it’s own right (which I might cover very soon!) – but I do want to cover the high-level routes open for most organisations to use Teams – in various ways. 

High-level Considerations 

From the outset, it is important to identify: 

  • What capabilities you want from a Teams solution 
  • What the migration path looks like 
  • Is it a journey that ends in a full shift to teams – or  
  • Does a hybrid solution becomes the likely outcome:  


I think it’s safe to say that many reading this post will have used Teams at some point in their working lives – whether using it themselves, using it due to this pandemic – or even joining a conference call with another organisation that uses Teams. Microsoft have done (probably) a better job of marketing Teams than ever before (Live Communications Server, Office Communications Server, Lync, Skype-for-Business – I’m looking at you!!)  and for the first time it feels like there is some real momentum behind a Microsoft UC platform. 

It’s a shame then that Teams is in many ways inferior to Skype for Business in terms of “Enterprise” voice functionality. It is undoubtedly a much stronger product in terms of look and feel, remote working and collaboration elements – and definitely the approach from Microsoft that it is a “cloud ONLY” solution is the right way to go – but the “PBX” capabilities are on the light side when compared to its predecessors.  

This isn’t necessarily a problem – Teams is not “new” and we’ve had time over the past few years to evolve our proposition for Teams. There are ways to fill in the “gaps” but it does highlight that when considering a Teams migration, due thought and diligence is applied to understand what functionality and architecture is required/desired – and to take appropriate decisions to achieve that. 

High-level concepts to consider include: (Not an exhaustive list!!) 

  • PBX Capabilities – what features are currently used on your existing solution (whether legacy/on-prem/hosted/etc) – are those features actively used and can/could they be replicated in a “Teams” environment?  
  • Resilience – what happens if Azure or Teams has an outage (this has definitely happened a few times!) – what impact does that have on areas of your business? 
  • Legacy estates – many of our clients have environments that are “far from straightforward” – is there significant analogue density, or cabling challenges, what does the network environment look like for voice – some of this is very much the same as considering a migration to IP voice full stop of course. 
  • Switchboard/Attendant Consoles – are there pinch-points in your organisation where a group of users field a significant volume of calls – how would that work in a Teams environment, how would you manage a larger telephone directory? 
  • Contact Centre – if your business has a contact centre, what do their requirements look like (again a larger conversation in its own right) – certainly there are ways to field most requirements in Teams, but part of the conversation as to the right route forward. 
  • Call Recording – including PCI / MiFiD II compliance requirements – how can this be achieved? 

Migration Path 

Depending on the answers to some of the above questions (and perhaps also what your wider IT strategy looks like) there are three likely scenarios that apply for most organisations: 

Migration to Teams for all voice requirements 

This would see you move all voice requirements to Teams – whether clients on desktop, mobile or traditional Teams-enabled IP Hardphones – with a shift for all PSTN numbers from your existing solution to Teams. Certainly there are a number of approaches within our portfolio that can support this and likely enable strong PBX capabilities to complement the Teams solution where appropriate. 

Hybrid Teams & Legacy PBX  

For many organisations there is likely to be a strong existing PBX capability – whether Avaya/Mitel/Cisco/etc – or an.other – and of course a wide range of deployment scenarios and solution ages/capabilities. There are a number of ways to link a legacy PBX environment to Teams and potentially this can provide a best-of-both worlds approach allowing users to deploy their client of choice (for this conversation I will assume that to be Teams!) but to retain existing PSTN connectivity and access to system features. Often users will find Teams to be significantly easier to deploy than PBX-based approaches to UC due to the ubiquitous nature of the solution – and as a “cloud” solution the ease of deployment for remote users, but marrying that with the reliability of their PBX, rich feature set offers the potential to have some level of resilience should “Microsoft” become unavailable at any stage… 

Hybrid Deployment with Gradual migration 

For many this is a journey that will not be immediate. There are many options to initially follow a hybrid approach but then over time gradually move PSTN and features from the legacy PBX to the Teams environment. From a “risk” perspective this can be a strong route to take – the key being to manage the “glue” in-between to ensure that the wider solution delivers what is needed throughout. 

The Options 

Whilst the wider marketplace is becoming ‘congested’ with a myriad of attention-grabbing products and headlines, the likely options to achieve these routes are as follows: 


Enablement of the Microsoft Phone System within Teams – effectively a carrier-grade solution that allows organisations to route calls from their SIP provider (us ideally!) directly into Teams via a Microsoft-certified Session Border Controller (SBC). 

This approach is typically the simplest route to enabling voice for Teams, without the need to consider as a “large project” and the cost overheads associated with that. 

It allows users to make and receive phone calls without needing to buy an expensive Microsoft Calling Plan. They can either migrate their existing DDI or have a new DDI as required. It will also work with a variety of endpoints – Teams-approved Handsets, the Teams desktop client – or indeed the mobile options too. 

Our offering in this space includes bundled inclusive call minutes and typically can be hugely cost-effective vs existing PBX costs (Support, line rental, call rates). We also add a great deal of functionality that most organisations need outside of the core Teams capabilities such as Advanced Hunt Groups or Advanced Routing Capabilities. 


This approach is broadly similar to the above – with a Microsoft-certified Session Border Controller (SBC) that allows you to connect both your PSTN provider (whether SIP or ISDN) – AND your PBX – directly into Teams – with the capability to route calls from both Teams and PBX to/from the PSTN – but additionally enables you to route calls between the two.  

This allows a number of concepts – from call forking allowing calls to ring on PBX AND Teams endpoints simultaneously, to allowing extension dialling between Teams and the PBX or to leveraging PBX capabilities for Teams endpoints. 

Every client has different requirements and we believe in choice, so we can support that SBC in multiple formats – or potentially a hybrid approach covering all bases – that includes: 

  • On-Prem SBC deployment (one or multiple locations) 
  • Privately hosted SBC(s) in one of your Data Centres 
  • Privately hosted SBC(s) in one of our Data Centres 
  • Publicly hosted SBC(s) – Azure, AWS, etc 

It’s also worth flagging that for any hybrid deployment linking to existing PBX(s) that network environment and transport become important concepts. You should ensure that your Teams partner has the capabilities to support LAN/WAN requirements too– something that we see as a key strength within Charterhouse. 


For organisations with wider requirements, either for PBX feature set  or potentially for global reach, there are a number of approaches whereby deploying a modern cloud-based voice solution can now support (via Direct Routing, see a theme here?) Teams as the endpoint of choice (again whether desktop, mobile or hardphone clients).  

This delivers all of the above capabilities for Teams integrated with PBX but as a single holistic solution, potentially with local breakout and dialtone in whichever countries you need to operate in. It also offers further potential for reducing costs and better integrating geographically disparate locations. 

Our solutions in this space have a significant range of capabilities over and above “dialtone” – from integration with various software platforms (CRM, ERP, etc) – to Call Recording – to full globally hosted Contact Centre solutions and beyond. 

Microsoft Requirements 

An important element of the solution that is often overlooked is the Microsoft licencing part of the equation.  Whilst many users may currently be using Teams “internally” there are a range of options to enable the necessary voice features. 

Ignoring the Microsoft offerings that effectively require MS Calling Plans (£££!) you will have the following options available: 

For small or medium-sized businesses (less than 300 users) you have 2 ways to get voice features: 

  • Buy an Enterprise E1 or E3 plan and add voice features individually 
  • Buy an Enterprise E5 plan with inclusive voice features 

*Note, in the UK, Microsoft also offers the Business Voice capability as an add-on but this is ONLY available with an MS Calling Plan (£££) – and offers significantly less capabilities than our Direct Routing approach. 

For enterprises (more than 300 users) you have the same options available:

  • Buy an Enterprise E1 or E3 plan and add voice features individually 
  • Buy an Enterprise E5 plan with inclusive voice features 

For education customers you can run with:

  • Buy an Education A1 or A3 plan and add voice features individually 
  • Buy an Enterprise A5 plan with inclusive voice features 

And for Government customers you can run with:

  • Buy an Education G1 or G3 plan and add voice features individually 
  • Buy an Enterprise G5 plan with inclusive voice features 

As you’ll see a similar approach for all sectors, but there are absolutely costs involved here from the Microsoft side – whichever of the approaches to Teams migration you are taking. As a strong Microsoft partner we can help with this side of things too. 


At this stage, I hope this has provided a useful high-level summary of the options available. This marketplace is already becoming convoluted with a wide range of white-labelled and obscure offerings and there is absolutely value to be found in the right partner that can work with you to understand your needs and goals, and to produce a roadmap for your individual journey that is realistic, deliverable and commercially viable. 

A recurring theme of this article is that of “choice”. Engage with us to discuss what you would like to achieve with UC and our commitment to you is that we will always provide direct and knowledgeable advice – whether for solutions within our portfolio or outside of it.  

Speak to the team


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