Plivo GetInput XML comes with inbuilt support for Automatic Speech Recognition. 

You can use GetInput XML to prompt users for inputs, and gather their voice responses in real time.

Gathered speech is transcribed and forwarded to the specified Action URL instantly. 

You may then use this transcription to identify the caller's intent and accordingly respond with another Plivo XML.

To learn more about Automatic Speech Recognition with GetInput XML, check out the detailed reference documentation here.