Picture a water meter in an apartment basement, a fault contact on a remote pumping station, or a control cabinet on a site with no Wi-Fi. Each sends a few bytes a day, and none sits near a network cable. NB-IoT was designed for exactly this kind of job. The short answer to “what is NB-IoT?” is this: a cellular technology for small amounts of data that runs on the existing base stations of mobile operators, reaches deep into buildings, and can run for years on a single battery.
NB-IoT is short for narrowband IoT: instead of wide channels for fast downloads, it uses a very narrow radio channel and pushes short messages through it as robustly as possible. Below you will see what that means for data rates, battery life and coverage, and where its limits are.
How does NB-IoT work?
NB-IoT is a standard from the mobile industry body 3GPP and was finalized in 2016 as part of Release 13. Technically it is a heavily slimmed-down version of LTE. An NB-IoT carrier occupies just 180 kHz, which is exactly one of the resource blocks that make up a normal LTE channel. Operators can place that carrier inside an LTE channel (in-band), in the unused guard band at its edge (guard-band), or on its own, for example in a former GSM channel (standalone). Either way, NB-IoT runs on existing cell towers and needs no infrastructure of your own.
Most of its range comes from repetition. When reception is poor, the device sends the same message many times in a row and the base station combines the copies. The standard allows up to 2,048 repetitions on the downlink and up to 128 on the uplink. That gives NB-IoT a maximum coupling loss of 164 dB, about 20 dB more than classic GPRS, which is why NB-IoT meters can still report from a basement or from inside a metal enclosure. The trade-off is that every repetition costs time and energy.
NB-IoT is also built around simple, low-cost devices. Modules work in half-duplex, never sending and receiving at once. There is no voice support, and a device does not hand over from one cell to another during an active connection; it only picks a new cell once it is idle again. The 3GPP design target is roughly 50,000 devices per cell. The device categories are called Cat-NB1 (Release 13) and Cat-NB2 (Release 14). Cat-NB2 mainly adds higher data rates and better positioning support.
What data rate does NB-IoT support?
The data rate is deliberately low, because NB-IoT is meant to carry readings, not files. The table below puts the peak figures of both NB-IoT categories next to LTE-M (Cat-M1), the second cellular IoT technology that many modules support alongside NB-IoT.
| Category | Bandwidth | Downlink (peak) | Uplink (peak) | Latency | Handover during a connection |
|---|---|---|---|---|---|
| Cat-NB1 (Release 13) | 180 kHz | approx. 26 kbps | approx. 62 kbps | 1.6 to 10 s | no |
| Cat-NB2 (Release 14) | 180 kHz | approx. 127 kbps | approx. 159 kbps | 1.6 to 10 s | no |
| LTE-M (Cat-M1) | 1.4 MHz | up to approx. 1 Mbps | up to approx. 1 Mbps | approx. 10 to 15 ms | yes |
These are theoretical peaks. Real throughput is much lower because devices share a cell and weak signal forces repetitions, but that hardly matters: a reading with a timestamp, battery voltage and signal strength rarely exceeds 50 to 100 bytes.
Latency matters more than raw speed. An NB-IoT message can take several seconds to reach the server, which is irrelevant for a meter reading but rules out real-time remote control. Large over-the-air firmware updates are possible, but slow and hard on the battery. If you move larger amounts of data regularly or run devices that travel, LTE-M is the better fit.
Which UK networks support NB-IoT?
In the UK, NB-IoT support is less uniform than many people expect. Vodafone runs the most established NB-IoT network and has stated that it reaches more than 98% geographic coverage, indoors and outdoors, for devices that can work at a signal level of -128 dBm. O2 (Virgin Media O2) built its low-power network around LTE-M first, and device makers’ UK network guides do not agree on how far its NB-IoT service extends. EE is listed in some of those guides with NB-IoT on band 3, but with coverage gaps, while Three does not currently offer a low-power IoT network. Since no single UK network covers the country on one technology, device makers often recommend a roaming IoT SIM.
In Germany, where our shop is based, all three major operators offer NB-IoT. Deutsche Telekom and Vodafone built their networks from 2017, and O2 Telefónica launched NB-IoT together with LTE-M for business customers in 2019. According to device documentation, Telekom mainly uses band 8 (900 MHz), Vodafone uses band 20 (800 MHz), and O2 uses band 20 and partly band 3 (1,800 MHz).
Wherever you deploy, coverage maps only show an outdoor prediction, and your phone’s signal bars say little because the phone often uses different frequencies. A device also registers only on the network its SIM is enabled for, and NB-IoT roaming agreements are far rarer than for phones. Test with the exact SIM and device in the final mounting position, lid closed, and look for several successful reports over a few days.
Does NB-IoT need a gateway?
No, and that is one of its biggest advantages. An NB-IoT device talks directly to the operator’s nearest base station, just like a phone, so there is no gateway to install, power and maintain. With many scattered sites that each have only one or two measurement points, every sensor simply brings its own connection.
It still does not work without any infrastructure. You need a SIM card or eSIM profile with NB-IoT enabled, the right access settings (above all the operator’s APN), and a server that accepts the messages. The Dragino CPL03-NB, for example, sends its data via MQTT, UDP, TCP or CoAP to an address you choose and delivers it as a JSON or HEX payload. Running costs shift from gateway hardware to a per-device SIM plan.
If you build your own hardware, you start one level lower. The RAKwireless RAK5860 is a WisBlock cellular module with the Quectel BG77 that supports Cat-NB2, LTE-M and optional GNSS. It also needs a core module, a base board and a battery, because according to the manufacturer USB power alone is not enough for stable radio operation. You control it with AT commands over UART.
How long does an NB-IoT battery last? PSM and eDRX explained
The 3GPP target for NB-IoT is ten years of operation on a 5 Wh battery when the device sends about 200 bytes per day. Whether your device gets there depends on two power-saving features that both the device and the network have to support.
PSM (Power Saving Mode) is the deepest sleep. The device stays registered on the network but switches its radio off completely and cannot be reached during that time. After sending, it stays reachable for the duration of the T3324 timer, then sleeps until the T3412 timer (up to roughly 413 days) expires or a measurement event wakes it. Because the registration is kept, waking up skips the energy-hungry connection setup.
eDRX (extended Discontinuous Reception) is the compromise. The device sleeps in cycles and briefly listens in between to check whether the network has a message for it. With NB-IoT, an eDRX cycle can be up to about 2.9 hours long. That makes the device reachable at predictable intervals, which suits applications that occasionally need to send it a command.
The biggest battery drain is not sleep but transmitting in poor coverage. According to its datasheet, the Dragino CPL03-NB draws about 10 µA at rest but up to 350 mA while transmitting. If weak coverage forces the module to repeat its message many times, each of those peaks gets longer. The sensor ships with a non-rechargeable 8,500 mAh lithium thionyl chloride battery and reports every two hours by default. How long that lasts depends on the reporting interval, the number of alarms and the signal at the mounting spot; a battery-life figure is always an estimate under specific assumptions.
Which frequency bands does NB-IoT use?
NB-IoT runs in the regular LTE frequency bands that an operator assigns to it. In Europe, three bands matter, and you should find them in any device datasheet:
| Band | Frequency | Typical use in Europe |
|---|---|---|
| Band 3 | 1,800 MHz | used by some operators (EE in the UK, partly O2 in Germany); weaker building penetration |
| Band 8 | 900 MHz | main NB-IoT band of Deutsche Telekom |
| Band 20 | 800 MHz | main band of Vodafone and O2 in Germany; widely used in the UK |
The table shows what to look for when choosing a device. For European use, a device should support at least band 8 and band 20, plus band 3 if you deploy in the UK; otherwise you are tied to a single operator. The low frequencies around 800 and 900 MHz pass through walls and floors better than band 3, which matters for basements and shafts, and broad band support protects you if an operator changes its band plan.
Outside Europe, other bands apply, such as band 28 in Asia and Australia or bands 5, 12, 13, 66 and 85 in North America. The Dragino CPL03-NB uses the Quectel BC660K-GL module and supports 17 bands in total, including bands 1, 3, 5, 8, 20 and 28. That makes it usable internationally if the SIM has NB-IoT access there.
What is NB-IoT used for?
NB-IoT is at its best with stationary measurement points that report rarely, send little and are hard to reach. The classic example is utility metering: water, gas and heat meters in basements and shafts report their reading once or several times a day. Fault contacts on pumps, tank levels, door contacts on remote equipment rooms and leak detectors are equally good fits.
A concrete example is the Dragino CPL03-NB, a dry-contact sensor in an IP67 enclosure. It detects whether a potential-free contact is open or closed, counts the openings and reports how long the last open state lasted. If a state persists longer than a configured time, it can raise an alarm. Its datalog feature stores readings during a coverage outage and sends them once the network is back. What a contact change means depends on the equipment you connect.
NB-IoT is a poor fit for anything that moves: without handover during a connection, vehicles and parcel tracking are better served by LTE-M. It is not meant for cameras, voice or sub-second responses either. Also plan how you will tell a sensor that is silent because nothing happened from one that lost coverage; a regular status report alongside the event messages solves that.
Is NB-IoT being switched off?
In the US, it already has been on one network: AT&T decommissioned its NB-IoT network in early 2025 and moved customers to LTE-M. In Germany, by contrast, Deutsche Telekom, Vodafone and O2 have not announced any NB-IoT shutdown. On the contrary, operators name NB-IoT as one of the successors for machine communication that still runs over 2G.
What is being switched off in Germany is GSM. Deutsche Telekom has announced that it expects to shut down its 2G network on June 30, 2028. Vodafone plans to switch off 2G for consumer and business customers in September 2028 and intends to keep GSM running for critical applications such as older alarm systems until the end of 2030. Anyone still running meters or fault alarms over 2G will have to migrate, and NB-IoT is one of the obvious candidates.
No radio technology lasts forever. Analysts expect some operators may follow AT&T, but NB-IoT to persist where it is used for smart metering, which includes Germany. For long-term plans, a module that supports both NB-IoT and LTE-M, such as the RAK5860, is the most resilient choice.
Where can you buy NB-IoT sensors?
Before you buy an NB-IoT sensor, it pays to run through the points from this guide. Check the frequency bands first: for Germany, band 8 and band 20 should be on the datasheet, and for the UK, band 3 and band 20 as well. Then decide which SIM the device will use, whether a suitable SIM is included or whether you will source an NB-IoT plan with its APN yourself. Make sure the sensor speaks a protocol your server or platform can accept, such as MQTT or UDP.
For battery life, the number on the box matters less than your reporting interval and the signal at the mounting spot. A datalog, timestamps and regular status reports make operation more reliable. If the measurement point moves, or you want to hedge for the long term, a device that also supports LTE-M is the forward-looking choice. Before a larger rollout, test one device at the real site.
If you are looking for suitable NB-IoT hardware, you can find sensors and modules in our NB-IoT category.
NB-IoT FAQ
Is NB-IoT the same as 5G?
Not exactly, but NB-IoT is officially part of the 5G family. NB-IoT and LTE-M meet the ITU requirements for massive machine-type communication in 5G and can operate in the same spectrum as 5G networks. Technically, though, NB-IoT is based on LTE and today mostly runs on 4G networks.
Does NB-IoT work in a basement?
In many cases, yes, because that is exactly what NB-IoT was designed for. Through repetition it achieves about 20 dB more range than GPRS, which lets it reach basements and shafts. Very deep locations or metal enclosures can still block the connection, and poor reception shortens battery life, so a test at the mounting spot is essential.
Does NB-IoT need a special SIM card?
Yes, the SIM has to be enabled for NB-IoT. Regular smartphone plans usually do not support it. You need an IoT SIM or eSIM profile from a provider that offers NB-IoT on the network and in the country you need, along with the matching APN. With the RAK5860, the SIM must also work at 1.8 V.