A user can access CRM form a blackberry device even when Mobile access has been restricted in the user settings for that user.
A user can log into CRM via a blackberry device even though the "Mobile Device Access" option has been set to "False" under Administration -> Users -> Users -> User in Question (William Dolan).
The cause of this issue was that the Blackberry device was being picked up as a Desktop device and not a Mobile Device.
To resolve this you need to get CRM to identify the Blackberry as a Mobile Device.
The way to do this is to first get the user agent string of the blackberry device the user has.
The following user agent string will be used in this example:
Mozilla/5.0 (BlackBerry; U; BlackBerry 9900; en) AppleWebKit/534.11+ (KHTML, like Gecko) Version/188.8.131.526 Mobile Safari/534.11+
There is a good article on blackberry user agent strings on the Blackberry Website:
Once you have the user agent string for this device, Navigate to Administration -> Advanced Customisation -> Devices.
Select the option to create a New Device, now add your user agent string in here.
Now if the user tries to log into CRM via a blackberry device and Mobile Access is restricted the user will not be able to log into CRM now.