You are the Office 365 administrator for your company.

You need to configure Microsoft Skype for Business Online to disable alerts for voicemail and instant messages to Windows Phones.
What should you do? or disable push notifications for Windows Phone devices by opening Lync admin center and navigating ti the

A.
In the Lync admin center, disable public IM connectivity.

B.
In the Lync admin center, disable the Microsoft Push Notification Service.

C.
Use the Set-CsPrivacyConfigurationWindows PowerShell cmdlet.

D.
Use the Set-CsHostedVoiceMailPolicyWindows PowerShell cmdlet.

Explanation:

Push notifications notify a user of events such as a new or missed IM invitation and voice mail. You can enable
Push Notification Configuration page. You can then click the site you want to edit, click the Edit menu, click
Show details, and clear the Enable Microsoft push notifications checkbox before clicking commit.
References: https://technet.microsoft.com/en-us/library/jj688162(v=ocs.15).aspx