Cell networks were built where people are. A lot of the things worth monitoring aren’t: wellheads, pump stations, livestock water tanks, rail cars, shipping containers, sensors on a ridgeline. When a device drives or floats out of coverage, it goes quiet, and you find out what happened later, if at all.
Until recently, the answer was a second radio. You added a satellite modem next to the cellular one, signed a second contract, paid for a second data plan, and built a second pipeline into your cloud. It worked, but it doubled the hardware, the firmware paths and the billing for a link most devices only need occasionally.
That’s changing. Satellite networks can now act like another cell network, reachable from a standard IoT module on the SIM already in the device. That’s the promise, anyway. Here’s what makes it hard, and what we’ve learned from testing it.
Why is satellite IoT harder than cellular?
Satellite isn’t cellular with a longer range. Your device and your software need to handle it differently.
- Small payloads. Think tens to a few hundred bytes per message: a position, a tank level, an alarm. It isn’t a pipe for logs, photos or firmware updates.
- Latency in seconds, not milliseconds. Messages can take seconds or longer to land, and some networks queue them until a satellite is overhead. Anything that expects a fast round trip, like a chatty protocol or a TLS handshake on every message, needs to be rethought.
- The device has to know where it is. Under the 3GPP standard for satellite IoT, the device uses a GNSS position fix to correct for satellite motion and timing before it transmits. Many modules can’t run GNSS and the cellular radio at the same time, so firmware has to sequence them, and that costs time and battery.
- Sky view and antennas. The device needs a clear view of the sky, and satellite runs on different frequency bands than terrestrial LTE. An antenna tuned for cellular, mounted inside a steel enclosure, won’t close the link.
- Power. Transmitting to a satellite takes more energy per message than transmitting to a tower a few miles away. Battery-powered devices need a budget for how often they’re allowed to use it.
- Cost per byte. Satellite data costs far more than cellular. Without rules about which messages may go over satellite, a misbehaving device can burn through a month’s budget in an afternoon.
- Failover is your problem. Something has to notice that cellular is gone, decide satellite is worth the cost, switch, queue what can wait, and switch back. Most of the time that’s your firmware, not the network.
None of these is a deal-breaker. All of them have to be designed for from the start, not added after the device ships.
How does same-SIM satellite IoT work?
The standards work that made this possible is 3GPP Release 17, which defined non-terrestrial networks (NTN) for NB-IoT and LTE-M. In plain terms, a satellite network can now present itself to a device the way a cell network does.
From there, it works much like roaming. If your connectivity provider has an agreement with a satellite network operator, the satellite network shows up as one more network your SIM is allowed to join. The device keeps its SIM and its identity, and traffic can come back to your cloud through the same path as your cellular traffic. You keep one SIM, one device record and one pipeline.
The conditions matter, though. You need:
- A module that supports NTN, with firmware that actually has it enabled, on the right satellite bands.
- A connectivity provider with a working satellite agreement that covers the places your devices go.
- The right antenna and mounting for the satellite bands, with a view of the sky.
- Firmware that knows the difference between a cellular link and a satellite one, and behaves accordingly.
When all four line up, it’s a real improvement over a second radio. When one is missing, you get a device that says “satellite-ready” on the box and never sends a byte over satellite.
”We have satellite” can mean very different things
Over the past several months we’ve tested satellite offerings from several connectivity providers on real devices, on the bench and in the field. Many advertise satellite IoT. In our testing, a lot of them connected only intermittently, in limited areas, or not at all. The marketing was ahead of the network.
That isn’t always bad faith. This is a new technology, and an announced partnership, a pilot and a commercial service are three different things that tend to share one press release. But if you’re planning a product around it, the difference matters. Before you commit, ask:
- Is it NTN on the same SIM, or a separate satellite modem and contract? Both are valid. They’re very different engineering and cost decisions.
- Is it commercially live where your devices operate today? Not “launching,” not “in trials.” Ask for the coverage area in writing.
- Which modules and firmware versions are approved to use it? Can you buy those modules in volume now?
- Can we test it before we sign? A provider confident in its network will put a test SIM in your device. If they can’t, that tells you something.
- Who handles failover? Does anything in their stack help, or does “support” just mean the SIM is allowed to try?
- What does a message actually cost, and does satellite data come back through the same endpoint as cellular, or a separate one you have to integrate?
If the answers are vague, plan as if satellite isn’t there yet.
What we’re building
After a lot of testing, we found one network that connects consistently. We’re working toward a partnership with them. On top of that partnership, we plan to build a platform that lets anyone get satellite connectivity for their devices without becoming a satellite expert first.
The idea is simple: pick a device that supports satellite, activate it, and have its data arrive in your cloud, with the cellular-to-satellite switching and the message budgeting handled for you. No second radio, no separate pipeline, no months of integration work to find out whether it connects.
It’s early. There’s no name or launch date yet, and we’ll share more as the partnership and the platform take shape. If you have devices that need to work beyond cell coverage and want to be among the first to try it, email us at [email protected]. We’d like to hear what you’re connecting. If you need cellular-to-satellite failover designed into a device now, that’s work we already do.