Cellular IoT spans a stack of competing standards, form factors and protocols — from the radio your device uses, down to the operator you buy connectivity from. This guide explains each layer of that stack, with clear comparisons and practical guidance on when to use what.
How the layers fit together
The table below maps the whole stack — click any layer, label or number to jump straight to that section of the page.
IoT connectivity options
How the device gets online
SIM Software
The OS running on the SIM
Why cellular for IoT?
Cellular wins when you need wide-area coverage you don’t have to build, the ability to roam across borders, and a single SIM that works out of the box anywhere. The trade-offs are module cost and power — which is exactly what the low-power cellular standards in the next section are designed to address.
Popular comparisons
All comparisons
Click the links in the table to learn more
| 2G | 3G | NB-IoT | LTE-M | LTE Cat-1 | 4G | 5G | |
|---|---|---|---|---|---|---|---|
| 2G | – | 2G vs 3G | 2G vs NB-IoT | 2G vs LTE-M | 2G vs LTE Cat-1 | 2G vs 4G | 2G vs 5G |
| 3G | – | 3G vs NB-IoT | 3G vs LTE-M | 3G vs LTE Cat-1 | 3G vs 4G | 3G vs 5G | |
| NB-IoT | – | NB-IoT vs LTE-M | NB-IoT vs LTE Cat-1 | NB-IoT vs 4G | NB-IoT vs 5G | ||
| LTE-M | – | LTE-M vs LTE Cat-1 | LTE-M vs 4G | LTE-M vs 5G | |||
| LTE Cat-1 | – | LTE Cat-1 vs 4G | LTE Cat-1 vs 5G | ||||
| 4G | – | 4G vs 5G | |||||
| 5G | – |
Popular comparisons
eSIM vs eUICC
eSIM and eUICC are often used interchangeably, but they’re not the same. eUICC is the chip standard that makes a reprogrammable eSIM possible — you don’t choose between them, you need both. We unpack eUICC properly in the SIM identity section.
Identity vs hardware
It’s easy to conflate these. ICCID and IMEI identify things (the SIM chip and the device); IMSI identifies a subscription; UICC and eUICC are the chip platform that carries them. Form factors like eSIM and iSIM — covered above — are about where that chip physically sits, not who it is.
Popular comparisons
IoT SIM vs consumer SIM
A consumer SIM is built for one user switching between a handful of operators. An IoT SIM is built for scale — bulk management, extended temperature ranges, longer product lifecycles, and remote profile switching without physical access to the device.
Why SGP.32 needs its own section
Consumer eSIM assumes a screen and a human. IoT devices often have neither. SGP.32 re-architects remote provisioning around an eIM and on-device or in-eUICC IPA so profiles can be managed at fleet scale, remotely, on devices that may only wake up occasionally.
Do you still need a VPN?
An APN decides where your traffic is routed; a VPN encrypts it. They operate at different layers, so they’re not alternatives — deployments on a public APN often add a VPN for secure transport, while a private APN can reduce or remove that need by keeping traffic off the open internet entirely.
What about MVNEs?
An MVNE (Mobile Virtual Network Enabler) provides the infrastructure and backend that MVNOs run on. You wouldn’t buy from one directly, but they sit behind many IoT SIM offerings.
Why data profile drives the whole stack
How much data your device sends, and how predictably, ripples back through every layer: it decides which cellular technology makes sense, how you’re billed, whether pooled or per-device plans fit, and how aggressively you need to optimise payloads.
