5G glossary: the acronyms, in plain English

Mobile networks have a habit of naming everything with three letters. Here are the ones that come up most on this site, in plain English. Each has its own anchor, so you can link to a single term.

If a term is missing, it probably deserves a guide of its own. The most important ones already have one: standalone vs non-standalone, eSIM and roaming.

5G NR

New Radio. The 5G air interface, meaning the radio technology between device and mast.

5G SA (standalone)

5G radio connected to a 5G core network, with no 4G anchor. Sold as 5G+ by EE and O2, and 5G Ultra by Vodafone.

5G NSA (non-standalone)

5G radio added to a connection that is controlled by the 4G core network through a 4G anchor.

5GC

The 5G core network. The software-based control and data system behind standalone 5G.

EPC

Evolved Packet Core. The 4G core network, also used by non-standalone 5G.

EN-DC

E-UTRAN New Radio Dual Connectivity. The technical name for a device using 4G and 5G together in non-standalone mode.

n78

The 3.3 to 3.8 GHz 5G band. The main UK 5G capacity band.

n28

The 700 MHz 5G band. Lower capacity but much better range and indoor reach.

mmWave

Millimetre wave spectrum above 24 GHz. Very fast, very short range. Plays little part in everyday UK 5G.

Carrier aggregation

Combining several frequency channels into one connection for more speed.

MIMO

Multiple input, multiple output. Using several antennas at each end to send parallel streams of data.

RSRP

Reference Signal Received Power. Signal strength, in dBm.

RSRQ

Reference Signal Received Quality. Signal quality taking load into account, in dB.

SINR

Signal to Interference plus Noise Ratio. How clean the signal is, in dB. Usually the best predictor of real speed.

Network slicing

Creating virtual networks with their own performance rules on a shared 5G standalone network.

VoLTE

Voice over LTE. Voice calls carried on 4G.

VoNR

Voice over New Radio. Voice calls carried natively on 5G standalone. EE calls it Vo5G.

RedCap

Reduced Capability 5G. A simpler, lower-power version of 5G for mid-range IoT devices. Needs standalone.

eRedCap

Enhanced RedCap. A further cut-down RedCap variant aimed at lower-end devices.

LTE-M

A low-power 4G technology for IoT devices that need mobility and moderate data, such as trackers and alarms.

NB-IoT

Narrowband IoT. A very low-power, low-data technology for static devices such as meters.

APN

Access Point Name. The setting that tells a device which gateway to use on a mobile network. In 5G standalone the equivalent is the DNN.

Private APN

An APN that routes traffic into a private network rather than the public internet.

CGNAT

Carrier-grade NAT. Many mobile users share public IP addresses, so devices cannot be reached directly from the internet.

Static IP

A fixed IP address assigned to a SIM, often public, so a device can be reached from outside.

IMSI

International Mobile Subscriber Identity. The identity stored on a SIM that the network uses to recognise it.

ICCID

The serial number of a SIM card, usually printed on it.

Multi-IMSI

A SIM holding several network identities and switching between them.

eUICC

The secure chip that can hold downloadable SIM profiles. The hardware behind eSIM.

eSIM

A SIM profile downloaded onto an eUICC rather than supplied on a plastic card.

iSIM

A SIM built into the device’s main processor or modem rather than on a separate chip.

SGP.22

The GSMA eSIM standard for consumer devices such as phones.

SGP.02

The older GSMA eSIM standard for machine-to-machine devices.

SGP.32

The GSMA eSIM standard for IoT devices without a user interface, commercially available from 2026.

eIM

eSIM IoT Remote Manager. The system that tells SGP.32 devices which profiles to download and enable.

SM-DP+

The server that securely prepares and delivers eSIM profiles.

MVNO

Mobile virtual network operator. A mobile brand that uses another operator’s network.

MOCN

Multi-operator core network. Several core networks sharing the same radio network and spectrum.

Steering

A home network directing a roaming SIM towards a preferred visited network.

Permanent roaming

A SIM staying on a foreign network indefinitely, common in IoT and restricted in some countries.

FWA

Fixed wireless access. Using a mobile network to deliver broadband to a fixed location.

Shared Rural Network

The UK programme to extend 4G coverage in rural areas by sharing masts between operators.