How to Sign Into Avaya Cloud Office Launch the Avaya Cloud Office Application.  If you are on a Windows Machine, this Application should be already installed and if you are on a Macbook you will need to install the Application from Mosyle Manager - For instructions on How to Install Avaya Cloud office on your Macbook, please click here. Launch the Application Avaya Cloud Office  Click Sign in with Google Choose your ISS Email Address The first time you sign in, it may ask you for permissions to use your Google Account. Click  Allow  on these options. Once you are signed in, you will receive a prompt to Open the Avaya Cloud Office App After you do this, you should be signed into the Avaya Cloud Office Software and can use your phone from your computer.