Voice Proxy using the Nexmo Voice API

Prerequisites

• A Nexmo Account
• Nexmo CLI (Command Line Interface)

Getting Started

Create a Nexmo App

Create an application and take a note of the application UUID:

nexmo app:create voice-proxy https://example.com/proxy-call https://example.com/event

Note 1: You may also want to save the private key file that is returned. You won't be able to get this again.

If you don't know the URLs for your proxy-call and event webhooks yet you can update them later e.g.

nexmo app:update APP_ID voice-proxy https://example.com/proxy-call https://example.com/event

Configuration

Copy the example.env to .env and update the content as appropriate:

cp example.env .env

Configuration is as follows:

Environment Variable	Required?	Description
NEXMO_API_KEY	Yes	Your Nexmo API key (Get from the Nexmo Dashboard)
NEXMO_API_SECRET	Yes	Your Nexmo API secret (Get from the Nexmo Dashboard)
NEXMO_APP_ID	Yes	The id generated when you created your Nexmo application.
NEXMO_DEBUG	No	Determines if interactions with the Nexmo API should be logged to the console. A non-falsy value will result in debug being on
PROVISIONED_NUMBERS	No	If supplied it should be in the format [{"country":"GB","msisdn":"NUMBER_1"},{"country":"GB","msisdn":"NUMBER_2"}]

Run the App

Start the application:

npm start

Usage

To indicate that a conversation between two users should be allowed navigate to the following replacing FROM_NUMBER and TO_NUMBER with e.164 formatting international numbers (e.g. 14155550123):

http://localhost:3000/conversation/start/FROM_NUMBER/TO_NUMBER

In a real system this conversation would be set up by an automated process.

To check the existing ongoing conversations navigate to:

http://localhost:3000/conversations

You should see a response such as the following:

[{
  "userA":{
    "realNumber":{
      "msisdn":"USER_A_REAL_NUMBER",
      "country":"GB"
    },
    "virtualNumber":{
      "msisdn":"USER_A_VIRTUAL_NUMBER",
      "country":"GB"
    }
  },
  "userB":{
    "realNumber":{
      "msisdn":"USER_B_REAL_NUMBER",
      "country":"GB"
    },
    "virtualNumber":{
      "msisdn":"USER_B_VIRTUAL_NUMBER",
      "country":"GB"
    }
  }
}]

This tells us there are two participants and gives us the details of their real number and their assigned virtual number.

• If you make a call from a UserA's real number to UserB's virtual number the call will be proxied to UserB's real number and the from number will be show as UserA's virtual number.
• If you make a call from a UserB's real number to UserA's virtual number the call will be proxied to UserA's real number and the from number will be show as UserB's virtual number.