Redmond Pie:

Unlike the many clones and pretenders looking to essentially copy the format, Spire simply installs the necessary files of Apple’s voice-recognition utility, requiring a server host and a legit iPhone 4S certificate to leave users with an all-singing, all-dancing port of Siri. In order to prevent such treachery, Apple seems to have added a “SetActivationToken” which stops Spire right in its tracks.