Microsoft is making available previews of its promised Skype for Business apps for iOS and Android.

Microsoft is allowing IT administrators to nominate up to four end users for iOS and four for Android to participate in the preview program for the coming apps. Admins need to apply by August 14, 2015, to be considered as one of the first batch of participants. Those selected will hear starting next week.

The new iOS and Android clients for Skype for Business -- the Microsoft unified communications product formerly known as Lync -- will be part of Microsoft's existing Skype for Business Preview program, according to an August 11 blog post announcing the coming availability of the apps.

The final versions of the new iOS and Android apps for Skype for Business will be available later this calendar year.

"If you have Lync 2013 on your iOS or Android device, you'll get the new Skype for Business app as an update later this year. Skype for Business mobile apps work for anyone on Lync Server 2013, Skype for Business Server 2015 and Skype for Business Online," explained Microsoft officials in today's post.

The coming new iOS and Android apps include support for a new navigation dashboard for contacts, calls and meetings, plus updated In-Call and In-Meeting functionality.Other new features include full screen video, enhancements to contact search, and more centralized appointment and conversation information.

Microsoft kicked off its Skype for Business rollout in April 2015. To date, the company has made available Skype for Business clients for Windows, the core Skype for Business service and its Skype for Business Server. Skype for Business clients for other operating systems are coming this summer, officials said earlier this summer.

Microsoft made its Skype for Business client for Windows Phone available in July.