Collecting DTMF

This example shows how to collect a DTMF string from the caller. It involves the Interaction turn which is created using the Interaction.Builder.

The first thing we need to do is to create the DtmfRecognition. This object contains the DTMF grammar used for DTMF recognition. There are a few built-in grammars specified in the VoiceXML specification. We are going to use digits.

Dialogue.java:

GrammarItem dtmfGrammar = new GrammarReference("builtin:dtmf/digits");
DtmfRecognition dtmfRecognition = new DtmfRecognition(dtmfGrammar);

Then we need to build the interaction. We are going to instanciate an Interaction.Builder for this task. There is two ways to get the Interaction.Builder object:

1. by calling the static method interaction
2. by using the constructor of Interaction.Builder directly

We'll use the first method.

Dialogue.java:

Interaction interaction = interaction("get-dtmf")

Note that we've used a static import for the interaction method:

Dialogue.java:

import static com.nuecho.rivr.voicexml.turn.output.OutputTurns.*;

Then we need to specify the prompts that we are going to use. This is done with the addPrompt method. Here we just use a SpeechSynthesis message.

Dialogue.java:

.addPrompt(new SpeechSynthesis("Type a number."))

To create the Interaction itself, we invoke the build method and we pass the DtmfRecognition object, meaning that we want to perform DTMF recognition immediately after prompts are played. We also need to specify the time-out value, i.e. the time before a no-input event is raised.

Dialogue.java:

.build(dtmfRecognition, Duration.seconds(5));

Now that we have an Interaction, we can execute it and receive the InputTurn which contains the result of this interaction.

Dialogue.java:

VoiceXmlInputTurn inputTurn = DialogueUtils.doTurn(interaction, context);

We now need to inspect the result in order to know what has been done by the user. We are going to deal with the following two outcomes

1. The user has typed a number
2. The user hasn't enter anything

Actually, other outcomes are possible (e.g. hang-up, error) but we'll ignore that for now for the sake of simplicity. The InputTurn contains a recognitionInfo property which gives us acces to the recognition result.

Dialogue.java:

Logger logger = context.getLogger();
if (inputTurn.getRecognitionInfo() != null) {
    JsonArray recognitionResult = inputTurn.getRecognitionInfo().getRecognitionResult();
    //Extracting the "interpretation" of the first recognition hypothesis. 
    String number = recognitionResult.getJsonObject(0).getString("interpretation");
    logger.info("Number entered: " + number);
} else if (VoiceXmlEvent.hasEvent(VoiceXmlEvent.NO_INPUT, inputTurn.getEvents())) {
    logger.info("Timeout.");
}

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Running this example

You can download or browse the complete code for this example at GitHub.This is a complete working application that you can build and run for yourself.

You can also clone the Rivr Cookbook repository and checkout this example:

git clone -b simple-dtmf-interaction git@github.com:nuecho/rivr-cookbook.git

Then, to build and run it:

cd rivr-cookbook

./gradlew jettyRun

The VoiceXML dialogue should be available at http://localhost:8080/rivr-cookbook/dialogue

To stop the application, press Control-C in the console.