Microphone input and output with SIRI?

Hello,
I recently developed an app for the Android that takes in microphone input from voice recognition, and has SIRI give an audible response to whatever was spoken into the microphone, and it is absolutely free. It doesn't cost a fraction of a cent per character for SIRI to speak, or per second for speech to text. I was wondering if there is a free 'replica' of the same 'interface' that Android uses, but for Unity on the Windows operating system platform? If not, is there something similar that is free (so I can talk to my characters in the game)?

Thank you,
Michael S. Lowe

 

Hello?

 

Anyone?