This is getting pretty weird. Windows Phone is now free, right? So if a phone maker builds WinPhones, do they pay Microsoft nothing for the same patents? Is that legal - to charge a patent royalty to device makers using somebody else's software - using no Microsoft code, while allowing makers of devices using Microsoft software to pay no software or patent fees?
Why would it not be legal - you can offer whatever licensing terms you like both on your own patents and on your own software.