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Amanda Cavallaro for Vonage

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Call Control Objects (NCCOs) | One Dev Minute

Welcome to One Dev Minute! This series is hosted on the Vonage Dev YouTube channel. The goal of this video series is to share knowledge in a bite-sized manner.

In this video, Amanda Cavallaro, our Developer Advocate, talks about the Call Control Objects, which are a set of actions that instruct Vonage how to control the call to your Vonage application. For instance, you can connect a call, send synthesized speech using talk, stream audio, or record a call.


A Call Control Object - or an NCCO - is a set of instructions that a voice call will follow.

An NCCO is composed of one or more actions. Their order is important, as it describes the flow of the call. Options are used to customize an action. A Call Control Object is represented by a JSON array.

In this example, we can see a connect action with the options to make a call from a given number to an endpoint of type phone with a number.

This second example is similar to the first one, but instead, it makes a call from a given phone number to an endpoint of type app, connecting to a client app, and we are also sending updates from the event URL.

You can join multiple calls into one conversation conference call.
In this example, you can see one action talk with a descriptive text showing you’re joining a conference. It's followed by an action that creates the conversation for the conference call.

We can also leverage speech recognition. Here’s a code snippet that shows how to handle a user's input.

We can accept Dual Tone Multi Frequency (DTMF), speech, or both.

You can learn further from the links below.


More resources related to NCCO:

NCCO Guide

NCCO Reference

NCCO Examples Collection

Call Flow

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