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Understanding “Office 365 E4” – Lync Enterprise Voice CAL Subscription

Update: 10/12/2015:

With the advent of E5 and Cloud PBX, E4 is no longer being promoted. E4 will appear on the Price List until June 30th, 2016. If your subscription plan come up for renewal prior to June 30th, 2016, you can renew to your current plan or transition into E5 or into E3 with Skype for Business Plus CAL subscription, a user subscription license (USL) version of Skype for Business Plus CAL.


As more customers move to/consider moving to Office 365/”the cloud”, or just moving their licencing to the subscription model, I’m increasingly getting questions around “Office 365 Enterprise E4”.

The Quick Answer

Office 365 E4 gives you everything in E3, plus a subscription way to buy the Lync Server Standard, Enterprise and Plus CALs (Client Access Licence) to use against an On-Prem Lync Installation. These CALs are the per user elements of Lync Server licencing.

  • This gives you the per user rights to use the full Lync Server feature set, including; IM/P, Conferencing, Video and Enterprise Voice.
  • You still have to buy the Lync Server and associated Windows Server/SQL Server licences to run Lync Server On-Prem (and any associated software assurance if you want it)
  • You can use Exchange Online Unified Messaging for your Lync Voicemail (over edge), included in your E3/E4 Pan.
  • You can have the same Lync SIP domain in Lync Online and On-Prem and spit your users between On-Prem and the cloud
  • Today, if you want Enterprise Voice (PSTN phone numbers) with Lync, you must deploy Lync On-Prem (or a Microsoft partner hosted solution).
  • Because you are buying an Office 365 E Plan which includes Microsoft Office, your Lync software client Licence is covered.
  • E4 is *not* a licence for upcoming PSTN Voice in Lync Online/Office 365.
  • There is an “Office 365 Education E4” and a “Government E4”,

This can be a vey cost effective way to Licence the user element of Lync Enterprise voice.

The Explanation

Microsoft split their Business/Enterprise Office 365 Plans into 4 options:


Hang on, you just said 4 options, I only see 3 there? If you scroll right to the bottom of the page you find the almost hidden E4 plan:


OK so E4 gives me “Lync Server 2013” ? , then we hit the hover:


OK, so now we’re told with a Plus CAL we need to purchase and deploy Lync Server  (but not been told what a Lync Server Plus CAL is).

Click through and we’re told:





“1. Lync enterprise voice capabilities require a customer to purchase and deploy Lync Server, either on-premises or in a hosted data-center, to enhance or replace traditional PBX systems.”

So, not the clearest messaging in the world, but essentially you’re buying Subscription Lync CALs, and you still have to Licence Lync Server On-Prem.


Disclaimer: I’m not a licencing expert, please always talk to Microsoft/Your Licencing Partner (LAR) to be sure you understand your options/are compliant.

About the author

Tom Arbuthnot

A Microsoft MVP and Microsoft Certified Master, Tom Arbuthnot is Principal Solutions Architect at Microsoft Collaboration specialists Modality Systems.

Tom stays up to date with industry developments and shares news and his opinions on his blog, Microsoft Teams Podcast and email list. He is a regular speaker at events around the world.


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Tom Talks Microsoft Teams and Microsoft 365 Collaboration news and opinions