Roaming on 5G depends on agreements between your home network and the visited network, and those agreements cover non-standalone 5G far more often than standalone. A UK phone abroad may get 5G, 4G only, or charges that depend on the country. A foreign or IoT roaming SIM in the UK may get 5G NSA, 4G or no 2G and 3G fallback, and some countries restrict SIMs that roam permanently.
Roaming is two networks agreeing to trust each other. Your home network vouches for your SIM, the visited network lets you on, and money changes hands in the background. Everything you experience when roaming, including whether you see 5G, comes down to what those two networks have agreed and built.
Outbound: a UK SIM abroad
Since the UK left the EU, roaming in Europe is no longer guaranteed free, and UK networks have mostly moved to daily passes or bundles, with some plans still including European roaming. Check your own plan before you travel; this changes often and differs by network and tariff.
For 5G specifically, your phone gets 5G abroad only if your network has a 5G roaming agreement with the network you land on. Many UK networks have these for non-standalone 5G in popular destinations. Standalone 5G while roaming is still rare anywhere, because the two 5G cores need to be connected in new ways. If you see 4G abroad on a 5G phone, that is usually the agreement, not your phone.
Travel eSIMs are an alternative: a separate eSIM profile from a provider that has its own agreements, used alongside your UK number. They can be cheaper for data, and some offer 5G where your home network does not.
Inbound: foreign SIMs on UK networks
This is the side that matters for IoT and for many business devices. Plenty of IoT SIMs used in the UK are actually foreign SIMs roaming onto UK networks. That can be a strength: one SIM, several UK networks, one contract across Europe. It also carries risks:
- Feature lag. Inbound roamers often get 4G or 5G NSA, not standalone, and may miss features like VoLTE or specific bands.
- Legacy cut-offs. O2 withdrew access to its 2G and 3G networks for inbound roaming devices from October 2025. A roaming device that relied on 2G fallback on O2 now has none there.
- Commercial changes. Roaming agreements are renegotiated. A network can change terms or steer traffic elsewhere.
- Permanent roaming rules. Some networks and countries restrict SIMs that never go home. The UK has been relatively relaxed, but a fleet deployed elsewhere may not be so lucky.
Steering
When a roaming SIM can see several networks, the home provider often steers it towards a preferred one, usually for commercial reasons. Steered SIMs may reject a stronger signal in favour of a cheaper network. Non-steered SIMs choose by signal. For a device on a hillside, that difference decides whether it works. See multi-network SIMs for more.
Roaming and 5G for IoT: what to ask a provider
- Which UK networks does the SIM use, and is it steered?
- Does it get 5G on each, and is that NSA or standalone?
- Is 2G or 3G fallback available anywhere, and for how long?
- Are there permanent roaming restrictions in the countries you deploy in?
- Can the profile be changed over the air if terms change? That is where eSIM earns its keep.
Questions people ask
Do I get 5G when roaming?
Only if your home network has a 5G roaming agreement with the network you are visiting. Many do for non-standalone 5G in popular destinations, but plenty of roaming still lands on 4G.
Is 5G standalone available when roaming?
Rarely, so far. Standalone roaming needs extra integration between the two operators' 5G cores, and it is in early deployment worldwide.
What is permanent roaming?
Using a foreign SIM in a country indefinitely, which is common for IoT devices. Some networks and countries restrict or ban it, so a roaming IoT SIM can be cut off even when it works on day one.
Can a roaming SIM use all UK networks?
Often more than one, depending on the home provider's agreements. That is how many multi-network IoT SIMs work. It does not mean the SIM gets every feature each network offers.