Cellular Connectivity for IoT

How cellular IoT works — network types, SIM technology, coverage considerations, and choosing the right plan

Concepts

Cellular networks are the most widely deployed wireless infrastructure on earth, making them a natural backbone for IoT deployments that need reliable, wide-area coverage. This article explains how cellular IoT works, what network types are available, and how to choose the right option for your project.

How cellular IoT works

IoT devices connect to carrier cell towers using the same radio infrastructure as smartphones, but with protocols and plans optimized for machine-to-machine communication. A SIM card in the device authenticates with the carrier network and establishes a data session routed through the platform.

The key difference from consumer cellular: IoT connections are typically low-bandwidth, high-reliability, and managed in bulk. A single account might manage 10,000 devices across 50 countries, each sending a few kilobytes per day.

Network types

Type	Bandwidth	Range	Power	Best for
LTE Cat-1	10 Mbps down	Standard cell	Moderate	General IoT, cameras, gateways
LTE-M (Cat-M1)	1 Mbps down	Extended range	Low	Asset trackers, wearables
NB-IoT (Cat-NB1)	250 kbps down	Deep indoor	Very low	Sensors, meters, static devices
5G mMTC	Varies	Standard cell	Low	Future high-density deployments

Most IoT projects today use LTE Cat-1 for general purposes or LTE-M for battery-powered devices. NB-IoT excels in deep-indoor or underground installations where signal penetration matters more than speed.

LTE-M in detail

LTE-M (also called Cat-M1) is purpose-built for IoT. It offers:

Power Saving Mode (PSM) — device sleeps for hours between check-ins, extending battery life to years
Extended Discontinuous Reception (eDRX) — reduces power during idle periods
VoLTE support — enables voice calls for wearables and alert devices
Firmware-over-the-air (FOTA) — enough bandwidth for remote updates

Available in 40+ countries, with the strongest coverage in North America, Europe, and parts of Asia Pacific.

NB-IoT in detail

NB-IoT trades speed for penetration and power efficiency:

20 dB better link budget than LTE — reaches basements, underground pipes, and thick-walled buildings
Ultra-low power consumption — 10+ year battery life on AA cells
Simple protocol stack — lower module cost than LTE-M
No handover support — not suitable for mobile devices

Best for static deployments: smart meters, environmental sensors, structural monitors.

Core concepts

SIM cards

A SIM (Subscriber Identity Module) is a secure element that stores the device's network identity. It handles mutual authentication with the carrier network — the device proves its identity to the network, and the network proves its identity to the device.

Platform SIMs work across multiple carriers without re-provisioning:

SIM IMSI: 295050123456789
Home network: Platform virtual carrier
Roaming: Automatic carrier selection per region

APN configuration

Every cellular device needs an Access Point Name (APN) configured to route traffic through the platform:

Setting	Value
APN	`soracom.io`
Username	`user`
Password	`user`
Auth type	CHAP or PAP

These settings are the same worldwide, regardless of SIM plan or local carrier.

Data sessions

When a device powers on, it establishes a data session:

SIM authenticates with the local carrier
Carrier routes the session to the platform
Platform assigns a private IP address and applies group policies
Device can send and receive data through the platform

Sessions can be monitored and controlled in real time via the Console or API.

Coverage and availability

Coverage depends on the carrier agreements in each region:

Global — 130+ countries via roaming agreements with 300+ carriers
Japan — Domestic coverage via multiple carriers with dedicated plans
North America — Full LTE-M and Cat-1 coverage via tier-1 carriers
Europe — Multi-carrier coverage across EU member states

Some regions offer dedicated local plans with lower latency and better pricing than roaming.

Choosing the right plan

Factor	LTE Cat-1	LTE-M	NB-IoT
Bandwidth needs	High (video, OTA)	Medium (telemetry)	Low (sensors)
Power budget	Wall-powered or large battery	Battery-powered (years)	Battery-powered (decade)
Mobility	Full handover	Limited mobility	Static only
Module cost	$15-30	$8-15	$5-10
Coverage	Standard LTE	Extended range	Deep indoor

When to choose LTE Cat-1

You need bandwidth above 1 Mbps — streaming video, frequent firmware updates, or gateway devices aggregating data from multiple sensors. Devices are wall-powered or have large batteries.

When to choose LTE-M

Battery-powered devices that send small payloads periodically. Asset trackers, environmental monitors, wearables. You need years of battery life with occasional connectivity.

When to choose NB-IoT

Fixed-location sensors in hard-to-reach places. Smart meters in basements, pipe monitors underground, structural sensors in concrete. Data volume is tiny (a few bytes per hour) and the device never moves.

Common challenges

Roaming restrictions

Some carriers restrict IoT roaming or impose permanent roaming limits (typically 90 days). Platform SIMs use agreements structured to avoid these limits, but regulations vary by country. Check coverage pages for country-specific notes.

Power management

Cellular radios consume significant power during transmission. For battery-powered devices, use PSM and eDRX to minimize radio-on time. Configure the platform to batch commands rather than polling, and set appropriate speed tiers to reduce transmission time.

How this works on the platform

The platform's connectivity service (Soracom Air) manages all the cellular complexity:

Carrier selection and roaming are automatic
Bandwidth tiers control cost without firmware changes
Session monitoring shows real-time connection status per device
Group policies apply routing, security, and service configurations in bulk

You configure connectivity at the group level and assign devices to groups. The platform handles carrier negotiations, IP addressing, and data routing transparently.

Soracom Air — Configuration and management
Platform Overview — Full architecture walkthrough
Quick Start — Connect your first device
Coverage — Check carrier availability by country