One of the areas where Microsoft’s Lync and Skype for Business (SfB) products have had the most success is in replacing business phone systems (usually known as private branch exchange, or PBX, systems). This success has come about because Skype for Business offers a robust feature set that matches or exceeds what legacy PBX systems offer, combined with a thriving ecosystem of devices and add-on products and all the benefits that come from its integration with Windows, Active Directory, Exchange and SharePoint.
So Close, Yet So Far
When Microsoft added Lync Online to the , it had a problem: customers who had bought the on-premises version of Lync would have to give up the ability to make and receive conventional phone calls through Lync Online. That forced customers to adopt one of a couple of different strategies: Use Office 365 only for presence, conferencing and instant messaging; deploy a hybrid environment and keep all the telephony features on-premises; or forgo Lync Online and stick with existing on-premises systems. product portfolio
The Bold New World of Skype For Business and PSTN Integration
SfB Enterprise Voice service offers the option to retain functionality provided by your on-premises deployment. This is helpful for businesses who need features that are currently available only with a specific on-premises Enterprise Voice solution.
And for the first time, customers have the flexibility to move people to the cloud at their desired pace, requirements and budget.
Depending on your needs, you can choose to have PSTN functionality provided by the Office 365 service or by your on-premises software–as shown in the adjacent diagram.
New Options for Business and IT
Business and IT users can now choose from a few different Microsoft telephony options. Here’s a brief summary of each.
Cloud PBX with PSTN Calling service
This is a service plan you can add to Cloud PBX to enable calling to landlines and mobile phones around the world. Users are homed in the cloud and are enabled for Cloud PBX with PSTN Calling provided by Microsoft. The PSTN Calling offering is an add-on to Office 365 that does not require an on-premises server deployment. However, PSTN Calling only works with Cloud PBX–you can’t use it with another PBX system.
Cloud PBX with on-premises PSTN connectivity
This option uses software on premises to connect your existing PSTN carrier, circuit, and contract with Office 365. Your users are homed in the cloud and are enabled for Cloud PBX, but their calling is processed through software on premises.
You continue to use your existing PSTN connectivity (either through a PBX, Gateway, Session Border Controller, or SIP Trunking connection) to source PSTN for the users who you move to the cloud. Once a user is moved to SfB Online and Cloud PBX, their phone number will route to any of the SfB clients for PCs or Smartphones as well as desk phones certified for SfB. Once ported, Cloud and legacy PBX users can call each other normally as well as make and receive PSTN calls using their full phone number.
Keep Your Homies Homed at Home
If you want to implement on-premises PSTN connectivity, Microsoft offers the following new integration options.
SfB Cloud Connector Edition
Cloud Connector is a hybrid offering that consists of a set of packaged Virtual Machines (VMs) that implement on-premises PSTN connectivity. Users in your organization, whether homed in the cloud are on premises, will be able to send and receive calls with landlines and mobile phones through the existing on-premises voice infrastructure.
SfB Server existing deployment
An existing Skype for Business Server or Lync Server deployment can implement on-premises PSTN connectivity as well. Users in your organization, whether homed in the cloud are on premises, will be able to send and receive calls with landlines and mobile phones through the existing on-premises voice infrastructure.
What To Do Next
At this point, you really need to understand your current and future functionality and feature needs. Then, start mapping them to the oncoming capabilities and packages offered, which you can learn more about here.