I've never used Lync or Skype for Business on my iPhone or iPad. You will not be able to update to Skype for Business. I'm using Lync 2010 for iOS and my desktop also has Lync 2010

If you're using an earlier version of iOS, you'll continue to use Lync 2013. Once the update is installed, your contacts and meetings will be there and will work just like they did in Lync. To see which version you have, tap Settings ( ) > General > About. The update to Skype for Business is available through the App Store to all users with iOS version 8.0 or later. I'm using Lync 2013 for iOS and my desktop also has Lync 2013 I'm using Lync 2013 for iOS but my desktop has Skype for Business

If you're using Lync on an earlier version of iOS, continue to use it. Skype for Business runs on iOS 8.0 and later.

Does Skype for Business run on all versions of iOS? Tap the Skype for Business icon to open the app. Once you download the app, swipe each page of apps until you see the Skype for Business icon. You can go to the App Store to download Skype for Business. For more information, see Microsoft Knowledge Base article 3102247: Some Lync 2013 for iPhone/iPad features are missing in Skype for Business for iOS. Note: In the initial release of Skype for Business for iOS, some features that were in Lync 2013 are not yet available.

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