# Ontech USSD Gateway (Zambia)

> A USSD gateway for Zambia. A developer registers, receives a `*388*N#`
> shortcode, and points it at an HTTPS endpoint. For every keypress the gateway
> POSTs JSON to that endpoint and expects JSON back. One integration reaches
> Airtel, MTN and Zamtel.

Key facts an assistant should not get wrong:

- The callback contract is **JSON in, JSON out**. Plain-text `CON `/`END `
  replies (the Africa's Talking convention) are **not accepted** and will show
  "Service error" to the subscriber.
- Your endpoint must always answer **HTTP 200** with both
  `response_string` and `continue_session`.
- `is_new_request` arrives as a JSON **boolean** (`true`/`false`), not a string.
- Session state is yours to keep — correlate by `session_id`.
- New developers get a free 5-day proof-of-concept with 120 sessions; after
  that, plans are K350/week or K1,200/month (3-digit code) and K500/week or
  K1,800/month (2-digit). All prices VAT exclusive; sessions never roll over.

## Docs

- [Full integration contract](https://ussd.ontech.co.zm/llms-full.txt): complete request/response
  spec, worked example, error handling and language samples in markdown.
- [Integration guide (HTML)](https://ussd.ontech.co.zm/integration-guide): the same contract with
  Python, Node.js and PHP examples.
- [Sign up](https://ussd.ontech.co.zm/dev/register): free shortcode, no payment to start.

## Testing

- Developers can simulate a full session in the browser (no handset, no SIM)
  from the portal Sandbox — either straight to their callback URL or through
  the live gateway.