By default Exchange 2010 limits users to a maximum of 10 devices. In the event that you get a new phone or tablet, and you are told that you have too many devices here is one way to fix it.
First, login to your Outlook Webaccess. If you dont know your address, let me know. When you log in go to the right side of the page and click on Options, then See All Options.
Now, once you are in options, click on Phone, and then Mobile Phones. Here it will show you all “associated” devices. These devices are considered trusted. If you know you dont have these devices anymore, lets delete them. As you can see some of my devices are quite old.
To delete a device, simply click on the device and hit delete. Do this for all old or unknown devices. This is also where you can do to WIPE a device in the event you have lost it.