Microsoft is retiring one of its Office 365 versions, and replacing it with an updated SKU before the end of calendar 2015.

The Office 365 E5 SKU will be replacing the current E4 version, officials said on July 13. The Office 365 E5 SKU will include Skype for Business (Lync) with support for features including Cloud PBX and Meeting Broadcast; new analytics features, like Power BI Pro and Delve Organizational Analytics; and new advanced security features, such as eDiscovery, Customer Lockbox, Data Loss Protection and Safe Attachments.

Office 365 E4 sells for $22 per user per month. It includes Skype for Business with Enterprise Voice and unified messaging; the full suite of locally downloadable Office apps; and Power BI for Office 365 (which is being superseded by Power BI pro).

Microsoft began testing three new Skype for Business services for Office 365 users, including PSTN conferencing and cloud PBX with PSTN calling. The new Skype for Business services are slated to be generally available before the end of calendar 2015.

Microsoft officials recently said the company would make available the updated version of its Power BI service starting July 25. This Power BI "2.0" release includes the new Power BI Pro service, which goes for $9.99 per user per month on its own.

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E4 will be retired when E5 becomes available. Net new customers will be able to purchase E5 or any combination of E1 and E3 with available upgrades to achieve Cloud PBX and PSTN capabilities. Existing E4 customers will have step up options to either E5 or E3 plus Cloud PBX. Customers who wish to maintain their licensing position, will be able to renew into E3 and Skype for Business Plus client-access license (CAL).

Existing Office 365 customers will be able to upgrade to E5 via step-up SKUs that charge the difference between what the customer currently has and E5 as the step-up price to E5. Add-on SKUs will also be available with customers who are maintaining on-premises licenses with Software Assurance.

Microsoft officials are not yet sharing publicly the price for the coming E5 SKU.