Will Skype for Business Online replace your PBX?


Microsoft’s cloud services are expanding at a rapid rate. In the last few years Office 365 deployments have moved from being primarily driven by migrating email to the cloud to now moving and adopting the entire evergreen productivity suite.

This is not only driven by wanting to make use of the services organizations have already purchased but also due to the expanding capabilities offered as standard both in E3 suites and newer E5 suites.

One such area where there’s been a lot of innovation lately is Skype for Business Online. First launched as Lync Online a few years ago this service has moved from simple IM and presence with PC-PC calling to a true mobile voice solution and conferencing replacement.

Why it’s time to put cloud voice on your roadmap

Many organizations I speak to – small and large are looking to hosted offerings to either replace – or supplement – their existing PBX. Smaller and medium organizations with fairly straightforward requirements who are currently looking at expensive hosted voice providers will find much of Microsoft’s new Cloud PBX offerings very tempting, and larger multi-national clients are finding that a Hybrid deployment can provide the best of both on-premises and cloud services.

Whilst it will not cover all use cases, and there’s still a case for on-premises and hosted PBX providers there is a lot to like in the new Skype for Business services.

What you’ll get with Microsoft’s new offerings

Microsoft have announced a number of new features that work with Skype for Business Online and can be used with on-premises Lync or Skype for Business, if its cloud-enabled:

Skype for Business Broadcast Meeting

Normal Skype for Business meetings are aimed at around 250 attendees in total, and are design for people to not just attend, but often participate in an unstructured way.

Broadcast Meeting is aimed at providing a way of projecting one (or few) to many meetings to a larger audience; for example town-hall company meetings, webinars or large events.

It has controls built into the Skype for Business 2016 client which allow presenting team to control the attendees experience or simply moderate inbound traffic. The viewers can access the meeting from most browsers with far less plug-in overhead that Skype for Business attendees currently deal with.

Skype for Business online

Currently in preview, Broadcast Meeting will work out of the box with Skype for Business Online and also work in conjunction with Hybrid deployments of Skype for Business On-Premises.

PSTN Conferencing

In essence, PSTN conferencing provides a dial-in number for Skype for Business meetings so that attendees without an audio device attached to their computer can dial-in from a normal phone. Increasingly – this isn’t necessary. I used to use this functionality extensively but due to the better capabilities in mobile client it’s often just as easy to connect any mobile using the SfB or Lync Online mobile client. There’s still a good case for using it – especially if it’s for a sales call or to allow an old conference phone to connect.

Third-party providers have been able to provide dial-in services for Lync and SfB Online for a number of years. Providers like PGi who have been in the game for a while will remain – the big difference is that now Microsoft are entering the fray.

Cloud PBX

There are two distinct pieces that make up voice in the cloud, Cloud PBX and PSTN Calling. Cloud PBX provides the capabilities for voice to happen, literally lighting up the private-branch-exchange features in the cloud ready to use as you see fit.
The features included are:

  • Call hold/retrieve, Transfer, forward, simul-ring
  • Team call, delegation
  • Qualified IP Desk Phones
  • Mobile clients with PSTN calling
  • Voice Mail
  • Call History
  • Basic 911
  • Complete Tenant Admin Experience
  • Deterministic Networking with ExpressRoute

With just Cloud PBX you need to provide a way for voice to connect to the PBX itself.

The first option – which is most appropriate for organizations who have a significant investment in Lync or Skype for Business on-premises is to Hybrid-ize their existing environment and use that as the the gateway to their PSTN and SIP trunk provisioning, as shown below:

Skype for Business Online

In this model it is expected that some users will remain on-premises but either remote offices or field-based workers will move to use the Cloud PBX, whilst still retaining their existing PBX infrastructure. This allows organizations deploying Skype for Business in larger settings to avoid the need for as many regional of branch-office type deployments and focus on the core infrastructure. If you haven’t yet deployed Skype for Business on-premises and simply want a way to connect your existing IP-PBX or SIP provision to Cloud PBX, Microsoft are releasing a pre-packaged set of virtual machines you can use to install a minimal topology.


PSTN Calling

The second option, suitable for organizations who have simpler voice requirements are likely to find the PSTN calling functionality attractive. The model for PSTN calling doesn’t require on-premises servers and effectively makes Microsoft the PSTN provider for the organization:

Skype for Business Online

Defining your strategy for Skype for Business Online adoption

With an idea of the road map ahead for Skype for Business’ online services it is important to have a clear idea and strategy of how you best plan to adopt and make use of the services available with the subscription. Often organizations adoption Office 365 will “light up” Lync Online – and now Skype for Business – as part of the mail migration. It is very easy to do this, but you need to be very cautious before giving the green light for anyone to just start using the services. The basic Instant Messaging and Presence functionality provides fairly little risk, and in general has very little bandwidth overheads. Deployments that make use of more functionality, even with just Skype for Business Online need to be more careful. Bandwidth planning for SfB is a necessity when planning to take advantage of PC-PC / Mobile calling, video, and meetings. Any serious use of voice requires Quality of Service, and if you are taking Cloud PBX and maybe PSTN Calling as well, then ExpressRoute for Office 365 with QoS with be critical to maintain quality. Many quick adoptions of SfB Online fail because there is no strategy and no plan for device purchase and implementation. If you are relying on laptop mic and speakers, conference attendees will suffer from mediocre quality and not only will adoption tail right off – you’ll probably have some serious questions to answer. The starting point is to make sure you have a clear vision and strategy when you start Skype for Business Online – and tie it into your wider productivity / Office 365 deployment and adoption strategy.


The new Skype for Business Online features make a big difference to the viability of Skype for Business for organizations weighing up on-premises versus the cloud. Online has a lot more potential and with hybrid functionality isn’t necessarily a cul-de-sac either. Defining the right adoption strategy for SfB and aligning it to the full Office 365 solution is important.

Steve Goodman

Steve Goodman

Principle Technology Strategist | MVP - Exchange & Office 365

Steve is a 5 times recipient of the MVP (Microsoft’s Most Valuable Professional) award from Microsoft, is a regular international conference speaker, podcast host, regular blogger, plus he is the author of a number of best-selling Exchange books. Steve has worked on a vast number of Exchange and Office 365 projects across customers large and small, often with complex requirements and would love to help you on too.

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