When it rolled out the public preview of Skype for Business -- a k a Lync -- in mid-March, Microsoft officials said to expect general availability of the new client, server and services to happen in April 2015.

This week, officials pinned a more specific date on the coming Skype for Business client. The coming Lync client replacement will be rolling out "as an update to Lync on April 14th as part of Office monthly updates," according to a Microsoft blog post, though IT administrators will be able to control how and when the Skype for Business update is rolled out to users.

Customers currently using Lync Online with Office 365 ProPlus, Office 365 Business Premium or Office 2013 will see the new Skype for Business client replace the Lync client. But those using Lync Server today will continue to see the Lync UI as the default experience.

A Microsoft spokesperson said the plan is to roll out the Skype for Business client "to all customers by the end of May." Microsoft also will be automatically updating the Lync Online Service to "Skype for Business Online" by the end of May.

The new Skype for Business Server will be available for download from Microsoft's Volume Licensing Service Center (VLSC) on May 1, 2015, the spokesperson confirmed.

As Microsoft officials noted in March, the public Office 16 preview currently includes the Skype for Business client preview.

While rebranding is a big piece of change from Lync to Skype for Business, there are some new features that Lync client users will see, too, as part of the transition.

The new UI will make Skype for Business look and feel more like the consumer version of Skype. The contacts list, presence indicators, buttons, icons and app sounds will be consistent. But many of the Lync-specific features, like the Quick Actions button, allowing users to IM or call a contact with a single click, will still be there, too.

Call Monitor -- which allows users to move back and forth between a full Skype for Business window and a compact view of that window -- will be part of Skype for Business client. The full set of emoticons available with Skype consumer will be available to Skype for Business users, as well.

There will be a new "Call via Work" feature available only to those with Skype for Business Server 2015. This feature allows enterprise users to make voice calls from the Skype for Business client. Call for Work routes voice calls from Skype for Business to the originator's desktop phone.

Skype directory integration also is only available to those with Skype for Business Server 2015. This feature allows Skype for Business users to connect over the Internet with existing Skype commercial users.

And despite the name change, Skype for Business will continue to run on the Lync backbone, not the Skype backbone, as officials said last year.