We say secret, but it appears that a Chinese government action has forced Vole to make the list public for the first time.
According to Ars Technica, Microsoft has revealed a few of those patents since as it has unleashed litigation against Android device makers. But for the most part, they've remained secret.
Now a list of hundreds of patents that Microsoft believes entitle it to royalties over Android phones, and perhaps smartphones in general, has been published on a Chinese language website as part of a Chinese government antitrust review relating to Microsoft's purchase of Nokia.
The patents Microsoft plans to wield against Android include things it has actually invented and patents that Microsoft acquired by participating in the Rockstar Consortium, which spent $4.5 billion on patents that were auctioned off after the Nortel bankruptcy.
It seems that Microsoft was compelled to produce the list to appease Chinese regulators, who feared that the software giant could become more aggressive with its patents after the Nokia purchase.
The longer list is divided into three sections: 73 patents that are said to be "standard-essential patents," or SEPs, implemented in smartphones generally, followed by 127 patents that Microsoft says are implemented in Android. The final section includes another section of "non-SEP" assets, which includes 68 patent applications and 42 issued patents.
There are some patents that Microsoft used against Barnes & Noble, including all 14 mentioned in this 2011 Network World article. Those patents include Nos. 5,889,522 entitled "System Provided Child Window Controls," and 6,339,780 "Loading Status in a Hypermedia Browser Having a Limited Available Display Area."
However there are some new patents, like 8,255,379 "Customer Local Search," 5,813,013 "Representing Recurring Events," and 6,999,047 "Locating and tracking a user in a wireless network through environmentally profiled data."
Nortel patents now owned by Microsoft include 5,982,324, which describes combining GPS with cell signals in an "efficient position location system" said to be used in Android phones. More Nortel patents are in the "general smartphone" section, such as No. 6,430,174, which describes a communication system that supports simultaneous voice and multimedia.
Vole has managed to build a huge patent licensing business by taxing Android phones without telling people what legal control they have. Vole collects between $1 billion and $2 billion from Android device makers paying royalties. By not disclosing which patents it had, it made it impossible for Google to come up with software which did not infringe.