SMS Proxy using Node and the Nexmo SMS API

This app uses the Nexmo SMS API to demonstrate how to build an SMS proxy for private communication between users. Each user sees only the other party's virtual number, not their real one.

Prerequisites

You will need:

• A free Nexmo account
• Somewhere to host this web app: Heroku or your local machine with ngrok both work well

Installation

git clone https://github.com/nexmo/node-sms-proxy.git
cd node-sms-proxy
npm install

Setup

Rename the config file:

mv example.env .env

Fill in the values in .env as appropriate; this will be your API key and secret, and the Nexmo number you want to use.

If you do not have a virtual number, you can purchase one via the dashboard.

Configure the number's SMS webhook URL to point to your application (if you are using ngrok then start your tunnel now), e.g. https://abcd1234.ngrok.io/webhooks/inbound-sms

Running the App

npm start

The application should be available on http://localhost:3000.

To change the port, try PORT=3001 npm start as an alternative command

Using the App

Register a conversation with the application so that mappings can be created between real user numbers and Nexmo virtual numbers. This is done by making a POST such as the following to http://localhost:3000/chat and replacing USER_A_NUMBER and USER_B_NUMBER with the real numbers of the parties involved:

POST /chat HTTP/1.1
Host: localhost:3000
Cache-Control: no-cache
Content-Type: application/x-www-form-urlencoded

userANumber=USER_A_NUMBER&userBNumber=USER_B_NUMBER

When you do this each of the users will receive a text. Replying to that text will allow the users to communicate anonymously with each other.