USSD quickstart

Create the projectCopy Anchor Link

1. Go to Projects and select New project.
2. Leave What should this project do? empty. If you describe the project there, AI drafts the flow for you instead, which is useful later but not for this walkthrough.
3. Set Start from to A blank canvas.
4. Set Channel to USSD.
5. Choose a USSD provider: the aggregator your short code is (or will be) provisioned with. It decides the request and response format the published app uses. You can change it later in the project's settings.
6. Enter a Project name, for example Airtime top-up, and select Create Project.

The canvas opens with one Menu node, Start, set as the Main menu. Every session begins there.

Add the other nodesCopy Anchor Link

From the node palette, add three more Menu nodes and one Router node, then rename them Amount, Done, Invalid and Check amount. The name is the text at the top of each node's editor. If you are new to the canvas, see Building flows.

Add them before configuring Start, because a menu option can only point at a node that is already on the canvas.

Build the Start menuCopy Anchor Link

Double-click Start to open its editor. A new project's Start node opens in the raw text editor, so switch it first:

1. Expand Advanced and turn Editor Mode to Structured.
2. Check that Menu Type is Main and Content Type is Text.
3. In Menu Message, replace the sample text with Buy airtime.
4. Under Menu Options, select Add Option three times and enter the labels 5, 10 and Other amount. Keys are numbered for you: 1, 2, 3.
5. Use the destination picker on each row (it reads Not connected until you choose) to send options 1 and 2 to Done, and option 3 to Amount.
6. Select Save.

The Preview on the right shows the screen as a handset displays it, and the counter shows how much of the 160-character limit you have used.

Ask for an amountCopy Anchor Link

Open Amount and, as before, switch Editor Mode to Structured.

1. Set Menu Type to Intermediary.
2. In Menu Message, enter Enter amount (1-100):
3. Leave Menu Options empty. The screen becomes an open prompt that accepts whatever the caller types. The canvas warns that the menu has no options; for a prompt like this that is expected.
4. Expand Output and set Output variable to amount. The reply is then available to later nodes as {{state.amount}}.
5. Save, then connect the node's output handle to Check amount on the canvas.

Check the amount with a RouterCopy Anchor Link

Open Check amount. Routers send the session down the first path whose condition is true.

1. Select Add first path and build the condition: state.amount greater or equal 1.
2. Add a second clause joined with AND: state.amount less or equal 100.
3. Turn on the Fallback path. It catches anything the path above does not match, including text that is not a number.
4. Save, then connect the first path to Done and the fallback path to Invalid.

Every path on a Router must be connected, or the flow cannot be built. See Router for the other operators and the expression editor.

Write the closing screensCopy Anchor Link

Open Done, set Menu Type to Last, and enter a message. A Last menu shows its text and ends the session, so it has no options.

For a message that works for both routes into Done, keep it general, for example Your top-up request has been received. Thank you.

Open Invalid, set Menu Type to Last, and enter Sorry, that amount was not accepted. Please dial again.

Dial it in the simulatorCopy Anchor Link

1. Save the project. The simulator runs the last saved version of the flow.
2. Select Simulate in the project header.
3. In the simulator, check Simulator Phone number, then select Simulate (or the call key on the dial pad) to start a session.
4. Type 3 and select Send, then type 250 and select Send. You should land on the Invalid screen.
5. Invalid and Done end the session, and the phone stays on that screen. To dial again, close the simulator and select Simulate again. Try 1, then 3 followed by 50.

As each screen resolves, the nodes it passed through are highlighted on the canvas, so you can see which path a reply took.