Skip to main content
SMS Gateway

Back to the list

Transactional notifications

The need

Your application has to reach someone right now: an order is confirmed, a payment failed, a server stopped answering. SMS is the only channel that arrives with no app installed, no account and no data connection.

How it works

A single POST to your gateway's API is enough. You do not say which phone should send: load balancing picks an available device and a SIM card that has not hit its daily quota.

Three guarantees matter on that path:

  • Idempotency. You attach an idempotency key to your call. If your code retries after a timeout, the message is not sent twice.
  • Status tracking. Every message carries a state, from queued to the carrier's delivery receipt.
  • Signed webhooks. Your application learns about a status change through a call signed with HMAC-SHA256, with replay protection.

What it changes on cost

The message leaves from your own SIM card. There is no per-message price charged by an intermediary, so no bill that grows with your traffic.

What it changes on privacy

Your customer's number and the message body never leave your machine. That is often the only way to get one-time code delivery past a compliance review.