Plivo charges for Automatic Speech Recognition based on the usage of Plivo’s Speech Recognition engine. 


It is possible that the caller may not have spoken for the duration for which Speech Recognition was enabled. 


In cases where simul-input (inputType=’dtmf speech’) is enabled, the caller may have chosen to enter a digit instead of responding with speech.


In the above cases, since Plivo’s Speech Recognition engine is engaged even if no speech is gathered, charges for Speech Recognition would be applicable.