Why frequency matters
Radio waves travel at the same speed regardless of frequency, but higher-frequency waves carry more data per second and lower-frequency waves travel further and penetrate obstacles more effectively. For mobile networks, this creates a fundamental trade-off: the spectrum that provides the fastest speeds covers the smallest area, and the spectrum that covers the most ground is also the slowest.
Networks manage this trade-off by using multiple frequency bands simultaneously — low-band for reach, mid-band for capacity, and (in limited cases) high-band for extreme speeds in dense hotspots. Your phone connects to the best available band at any given moment.
The main UK 5G bands
The n78 mid-band: the UK's main 5G workhorse
The 3.4–3.8 GHz band (n78 in 5G NR numbering) is the primary 5G band in the UK. It's where all four operators have deployed the majority of their 5G capacity. It offers good speeds — 100–600 Mbps in real conditions — with a manageable cell radius of 1–5 km in most environments. If you're getting 5G in a UK town or city, you're almost certainly on n78.
The limitation of n78 is building penetration: it doesn't pass through walls nearly as well as lower-frequency bands. Indoor 5G at n78 is noticeably harder to achieve than indoor 4G.
The n28 low-band: 5G that actually covers rural areas
The 700 MHz band (n28) is where 5G starts to offer genuine rural reach. EE and Three have made significant low-band 5G deployments. A single n28 mast can cover over 20 km in open terrain, making it viable for the countryside in a way that n78 never will be. The speeds are more modest — typically 10–150 Mbps — but that's still a significant upgrade on rural 4G in congested areas.
Low-band 5G also penetrates buildings better than n78, making it the more useful band for indoor use in rural areas where you do have 5G.
What about mmWave (26 GHz)?
The 26 GHz band (n258) represents the upper limit of current 5G technology — extraordinary speeds of 1–4 Gbps, but with a range measured in hundreds of metres and almost zero building penetration. It's currently only deployed in isolated hotspots in the UK (stadium trials, transport hubs) and isn't a meaningful factor in everyday coverage decisions. For our purposes, mmWave exists but you're unlikely to encounter it.
Frequently asked questions
Why does my phone show 5G but the speed feels like 4G?
You're probably on low-band 5G (n28, 700 MHz). Low-band 5G has roughly similar peak speeds to fast 4G — the benefit is reach and capacity, not dramatically higher individual speeds. True speed improvements come from mid-band 5G on n78.
How do I know which 5G band my phone is using?
On iPhone, there's no built-in display, but third-party apps can show band information. On Android, some devices show the band in the network settings; others require a field test mode (dial *#*#4636#*#* on many Android devices). The presence of 5G UC, 5G+, or similar indicators on some networks suggests you're on mid or high-band rather than low-band.
Does my phone need to support all 5G bands?
Your phone must support the specific bands your network uses. Most flagship phones sold in the UK since 2021 support n78 (the primary mid-band) and n28 (low-band). Budget 5G phones sometimes only support n78, missing out on low-band rural coverage. Check your phone's spec sheet for its 5G NR band list.