Reading mobile money confirmations in real time

The need

You sell online in a country where people pay by mobile money. The operator confirms every payment by SMS to the merchant's number, immediately. An API, when one exists at all, takes weeks of paperwork, a registered company, a minimum volume, and often a cut of each transaction.

Meanwhile the confirmation you need is already arriving, on a phone, as a text message.

How it works

The SIM that receives the operator's confirmations is one of the SIM cards paired with your gateway. From there:

The message arrives on the phone and is recorded by the gateway, on your own machine. An operator writes from a short code or a name, not a phone number: add it to Senders to record in Settings > Reception, or it will be refused like any unknown service. The Activity log shows its exact spelling the first time it writes.
A webhook calls your application as the SMS lands: subscribe it to message.received on the Webhooks page. The call is signed with HMAC-SHA256, so you can prove it came from your gateway, and it carries the identifiers of the message, never its text.
Your code reads the message through the gateway's API, with a key limited to the Read scope: GET /api/v1/messages/{id} returns the sender and the text.
Your code checks the sender, reads the amount and the reference, and marks the order paid.

Nothing is polled and nothing waits: the webhook leaves as the SMS lands.

What you should know before building on it

The message format belongs to the operator. They can change the wording without telling you, and a parser written on the old wording then stops matching. Log what you could not parse, and watch that log.
An SMS is not a proof of payment. It says what the operator sent to that number. For an amount that matters, confirm against the operator's own statement or API before delivering anything irreversible.
Keep the receiving SIM for that, on a phone that stays on charge. A confirmation that arrives while the phone is off is read when it comes back, not lost, but it is read late.
Check your operator's terms: what you may automate on a mobile money account is their rule, not ours.

What it takes

A paired phone, the SIM that receives the confirmations, the operator's sender recorded in Settings > Reception, a webhook on message.received, an API key with the Read scope, and one endpoint in your application. The gateway holds the messages; the decision to accept a payment stays in your code.