Costly Mistakes People Make with Skype For Business Voice | Pt 16 min read

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Voice has always been a difficult domain for most Service Providers, Microsoft or non-Microsoft. It is inherently complex, even more so now with the convergence of technology, communications and telephony.

There are many misconceptions in the marketplace about Skype for Business Cloud PBX, PSTN calling, and full Enterprise Voice – what it is, and what it isn’t, and I’ll aim to clarify this here.

Cloud PBX vs PSTN Conferencing vs PSTN Calling vs Enterprise Voice

These days we see both partners and customers using these terms interchangeably without truly understanding the difference between them. Indeed, even some of the most senior technical minds struggle to differentiate them.

Indeed, even some of the most senior technical minds struggle to differentiate them.

However the difference is significant and being able to communicate this to a customer may make the difference between winning and losing the sale. So here is the lowdown on each of them.


With a PSTN conferencing add-on, any Office 365 user can create online meetings, host conferences, invite external parties to participate and dial out to any PSTN party. Delivering this is very simple, it is just an add-on to the E1 or E3 Office 365 SKU and can be purchased directly from Microsoft.

PSTN Conferencing is available in almost 66 countries from Microsoft including Australia, Singapore, New Zealand, UK and USA.

There is a common misconception, that PSTN conferencing enables users to make and receive calls using their Skype for Business client, this is not true. PSTN conferencing does not give/assign a number to each user and enable them for PSTN.

PSTN conferencing enables remote/third party participants to join meetings/conferences hosted by the Office 365 user via dial in or dial out. And any user wishing to organise PSTN conference has to have the PSTN conferencing license assigned to them.


Adding Cloud PBX to an existing O365 plan provides customers with the ability to enable call management in the cloud. It enables them to use Skype for Business as a PBX, with features like call answer, caller ID, call forwarding, simultaneous ringing, call history, call hold, call transfer, call waiting, voicemail and music on hold.

However, with Cloud PBX on its own, you cannot dial out to any PSTN or receive call from outside, you have to either subscribe for PSTN Calling service from Microsoft (as at November 2016 available in the USA, UK and Puerto Rico) or integrate Cloud PBX with your existing on-premises telephony infrastructure using either Cloud Connector (a bunch of VMs) or deploy on-premises Skype for Business Server with telephony infrastructure and integrate with Cloud PBX

In a nutshell, to provide ability to users to make and receive calls with people outside the organisation you have to do the following two things:

  1. Purchase Cloud PBX add-on for each user who needs this functionality
  2. Integrate Office 365 Cloud PBX add-on with either on-premises telephony infrastructure
    purchase Microsoft PSTN Calling plan (for international availability visit ) and add it to your subscription.

In Australia and the Asia-Pacific region, as at November 2016,the only option for Cloud PBX is to integrate it with either a customer’s on-premises telephony infrastructure (which requires a bunch of Virtual Machines running) or create hybrid environment with an on-premises Skype for Business server with telephony integrated.

So while it is called “Cloud PBX” in order to use it as a full-PBX replacement it does require on premise equipment.

Even after integrating Cloud PBX with on-premises telephony and enabling PSTN service with Office 365 you would still be missing few features

If you do go down that path, even after integrating Cloud PBX with on-premises telephony and enabling PSTN service with Office 365 you would still be missing few features e.g. Response Groups (hunt groups for call queuing), IVRs (playing Interactive Voice Response to users calling your main line number etc.), Auto Attendant and end-to-end Quality of Service etc. – although these are on the roadmap of Microsoft to add to Cloud PBX and enable on Office 365 down the track.


On 1st Dec 2015, Microsoft launched PSTN calling plans in USA (Domestic and International) which enables Office 365 users subscribed to Cloud PBX to make and receive calls outside their organisation. To be able to make/receive calls outside organisation you also have to either subscribe to a Domestic Calling Plan or International Calling Plan on top of Cloud PBX.

Microsoft has since added PSTN Calling to other countries and a full list of countries where voice is available via Office 365 can be found at


Now let’s discuss the big giant that is “Enterprise Voice” and includes all the features of Cloud PBX, PSTN Conferencing, PSTN Calling and advance features like Response Groups, IVRs, Auto Attendant, and end to end Quality of Service etc.

It may surprise you to know that all these features and more are now available from a single platform based on a 100% cloud solution without need of any on premises equipment. No-CapEx is required for any on-premises telephony equipment, and there is no-CapEx for any server on-premises. Furthermore there is no CapEx for any on-premises telco termination (PRI or SIP trunk etc.) and still you get all the above features.

Private cloud voice specialists such as OBT work closely with Microsoft Office 365 partners to deliver Full Enterprise Voice functionality for SMB companies, whether they are on Business Essentials/Premium, Education/Enterprise/Government E1/E3 or E5 plan.

In Conclusion

While every new release to PSTN Calling takes it a step closer to replicating full Enterprise Voice functionality, there is still a significant gap between the public cloud offering, and the full Enterprise Voice experience that Skype for Business capability.

There are also other advantages gained by utilising private cloud Enterprise Voice such as no pre-payment on PSTN calling, accounts not being automatically suspended if pre-payments are not made.

Further, not every customers is in a position to migrate away from their existing telco. They may be in current contracts that include a package deal around internet links, voice, mobile phone fleet – often a bigger expenditure than the PBX calling component – and this impacts on their decision around what PBX they use.

Or for their own reasons a customer may just wish to retain the relationship they have with their existing telco provider.

The Opportunity

This represents a massive opportunity for partners who can wrap their head around voice and get a jump on the rest of the market as  “unified communications” – a single integrated platform seamlessly delivering EVERY aspect of communication – will undoubtedly become the norm for businesses large and small within the next 12-36 months as legacy phone systems phase out.

The race to own customers’ voice needs is on and providers from all walks are clamouring to re-invent themselves.

The race to own customers’ voice needs is on and providers from all walks – Telcos, technology providers and VoIP/PBX providers – are clamouring to re-invent themselves and position themselves to meet this growing demand from customers who want a single and robust platform that meets all their technology and communications needs – not just voice, but also video and conferencing.

And as customers get fed up with trying to integrate multiple disparate solutions into their Office 365 platform, and live with sub-standard solutions, providers who can offer a truly end-to-end service encompassing all aspects of mission-critical communications and technology will retain their customers for longer and enjoy far more annuity revenue.