Using the Passthru applet, you can get Exotel to talk to your Application URL and pass on details about the incoming call as and when it happens. Your application can now process this information to decide which path (success/failure) the flow should take next. This applet helps to dynamically control the flow as well as store the call details in your CRM system or other applications.
Right now, it is possible only to make a binary decision with Passthru. For example, you can return a 200 OK for choice A and 302 Found for choice B.
For complete list of parameters, refer here.