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Asterisks

Introduction

What USSD is, what Asterisks does for you, and the five steps from sign-up to a live shortcode.

What USSD is

USSD is the short code menu you get when you dial something like *384*55# on any phone. It works on every phone, including basic phones with no internet, which is why banks, mobile money, utilities and schools across Africa use it.

Asterisks Pay
1. Check balance
2. Send money
3. Buy airtime
0. Exit
A USSD screen: a short message and numbered options. The caller types a number and presses Send.

What Asterisks does

Asterisks lets you build that menu by dragging screens onto a canvas and joining them up. No code is needed for most apps. You test it in a phone preview in your browser, then publish it to your shortcode.

Asterisks remembers where each caller is in your menu, checks their answers, talks to the aggregator (the company that gives you the shortcode) in its format, and bills each session from your session balance.

Tip: New accounts get their first 100 sessions free. After that, each session costs GHS 0.025, paid from your session balance. The free plan has no monthly fee.

How a session works

  1. A customer dials your shortcode

    They dial something like *384*55# on their phone.

  2. The aggregator sends the request to Asterisks

    Your aggregator (Hubtel, Nalo, Arkesel or Africa's Talking) passes the request to the address Asterisks gave you when you deployed.

  3. Asterisks shows the right screen

    It runs your app, shows the next screen, saves any answers, and calls your systems if you added a Send Data step.

  4. The session ends

    On an End Session screen, the call closes. If you set a callback URL, Asterisks sends the caller's answers to your system.

The five steps to go live

StepWhat you doTime
1. Sign upCreate an account with your phone number.1 minute
2. BuildCreate an app and add your screens.5 minutes
3. TestTry it in the phone preview in your browser.2 minutes
4. DeployPublish it to your shortcode and copy the callback address.1 minute
5. ConnectPaste that address into your aggregator’s dashboard, then dial.2 minutes

Ready? Follow the Quickstart. It walks through all five steps with a real example.

Words you will see

WordWhat it means
ShortcodeThe code callers dial, like *384*55#. You get it from your aggregator.
AggregatorThe company that connects your shortcode to the mobile networks: Hubtel, Nalo, Arkesel or Africa’s Talking.
AppOne USSD service you build in Asterisks. Each app can be published to one shortcode.
ScreenOne message the caller sees, such as a menu or a question.
SessionOne call, from dialling to the last screen. Billing is per session.
VariableA saved answer you can reuse later, written in double curly brackets, like {{name}}.
Callback addressThe web address Asterisks gives you when you deploy. Your aggregator sends every request there.