Block WPD devices and MTP, PTP protocols over USB in windows 7,8

we Can block USB removable devices on all our workstations  but when someone plugs in a iphone, sony,Samsung or any android smart phones into the system, it acts as a removable storage device do to the fact it it is using MTP not usb mass storage device protocol which now becomes a security threat to our organization

Do the steps below :

Wrok group:
start->run-> gpedit.msc-> Computer configuration -> Administrative Templates -> System->Removable storage Access -> WPD Device denay read/write access -> enable

Start -> Run -> gpupdate /force.

For dmoain(Server 2008,R2, 2013):

Start -> administrative tools-> group policy management(expand your forest)->right click your domain ->create gpo inthis domain -> right click your gpo -> edit->Computer configuration -> Administrative Templates -> System->Removable storage Access -> WPD Device denay read/write access -> enable->enforce policy 
Start -> run-> gpupdate-> restart the server