How do Iridium 9603 messages get to your own server?

Every message sent by an Iridium 9602 or 9603 — and by the 9604, whose satellite side is also SBD — first reaches Iridium's SBD ground gateway. From the gateway to your server, Iridium offers three delivery methods; the difference is who builds and maintains the stage in between.

1. Email

The gateway sends each message as an email attachment to an address you specify. It is the simplest to set up, but your software has to collect the mail, extract the attachment and parse it, and a delayed or blocked email is easy to miss.

2. DirectIP

The gateway opens a TCP connection and pushes each message to a server you run. You need a fixed public IP and firewall rules and must implement the DirectIP message format; to send a message to a device (a downlink), your server connects back to Iridium. Handling downtime and dropped connections, and confirming delivery, are yours to design and monitor.

3. Iridium CloudConnect

Iridium's delivery method built with AWS: messages are converted to JSON and placed in Amazon SQS queues in the customer's AWS account, over a dedicated connection between Iridium and AWS rather than the public internet. There is no receiving server to run, but you need your own AWS account, cross-account authorisation, and your own code to read the queues, send downlinks and track their status.

With SBD CC, your server does two things

• Provide an HTTPS URL for uplinks and answer with a 2xx within 10 seconds — including when the same message arrives twice (check its ID).
• To send a message to a device, call the SBD CC API with the token N3D issues you.

SBD CC handles the rest: uplinks are signed with HMAC-SHA256 so you can verify the source; if your server does not answer, it retries for 72 hours; downlink status changes (queued, delivered, rejected, expired) are pushed to you; whether messages are kept is your choice in the console, and with storage on they are backed up for a year and retrievable through the API; and if anything failed the previous day, you get an email. You do not need an AWS account of your own. See SBD CC.

How much fits in one message

An Iridium SBD message carries up to 340 bytes from the device (mobile-originated) and up to 270 bytes to the device (mobile-terminated), the same for the 9602, 9603 and 9604. For photos or voice, move to the Iridium Certus 9704, which uses IMT, and IMT CC.