You support a Skype for Business environment.
Unified Messaging has been configured in the existing Exchange 2013 environment as part of the Skype
for Business project. You plan to deploy Enterprise Voice for all users, including users who have Skype for
Business Phone Edition devices that connect by using a LAN cable and a USB cable.
When a test user signs into Skype for Business, a prompt is displayed requesting user credentials for the
Phone Edition device. The user logs in and after a delay, a yellow warning triangle appears on every test
Phone Edition device.
In reviewing the device for errors, you discover that Exchange integration is failing with the following error:
"Connection to Microsoft Exchange is unavailable. Please contact your support team."
Logs from the Skype for Business Phone Edition device are displayed in the Exhibit 1. Click the celog
button.

Internet Information Services (IIS) logs from the Exchange server are displayed in Exhibit 2. Click the iislog
button.

You need to ensure that the device can authenticate to Exchange Web Services.
What should you do?