Steered vs unsteered multi-network SIMs: what's the difference?

Full bars on the screen, but nothing loads. Most of us have been there. A multi-network SIM can connect to more than one UK network, and how it picks between them changes how it feels in real life. There are two ways of doing it.

A steered SIM has a preferred home network. Your phone is nudged towards that network wherever it can, and it usually only moves to another network when the preferred one is unavailable. This is a standard technique in roaming, often called steering of roaming.

The catch is that the SIM can hold on to the preferred network even when the signal is poor. You may see bars on the screen but a slow or unstable connection. Moving to another network can also take longer, because the SIM waits until the preferred network has dropped out.

An unsteered SIM has no preferred network. It treats EE, O2, Vodafone and Three equally, so it isn't trying to hold on to one of them. If your network drops out completely, it moves to another one. If you have full bars but no internet, switch network manually from your phone's settings. FlexiFone SIMs work this way.

It matters most in patchy areas: villages, valleys, hills, train routes, and buildings with thick walls. With no preferred network, the SIM isn't trying to hold on to the wrong one.

Three honest points. First, unsteered does not mean fastest. The phone picks based on signal, not speed, so on a busy network the connection can still be slow. Second, automatic switching happens when signal is fully lost. If you have full bars but no internet, change network yourself: on an iPhone go to Settings > Mobile Service > Network Selection, turn off Automatic and pick a network (the path varies by phone). Third, a multi-network SIM roams on the UK networks, which can mean lower priority at busy times and slightly higher latency than a standard SIM.

FlexiFone has no preferred network, so nothing holds your SIM on a network that isn't working for you. You can also block one network in your account (Manage SIM > Network Blocking). If your main SIM is on Vodafone, block Vodafone on your FlexiFone SIM and it only uses EE, O2 and Three, which gives you a real second option when Vodafone is weak.

Read the provider's own description, and test it. Go to a spot with weak signal, open your phone's network settings, and see whether the SIM sticks to one network or moves to a better one. Providers can also describe themselves differently: some call their SIM "un-steered" and some do not describe it at all, so the test is more reliable than the label.

Is FlexiFone steered or unsteered?
Unsteered. There is no preferred home network.

Can I choose the network myself?
Yes. You can switch manually from your phone's settings, and you can block one network in your account.

Why do I have full bars but no internet?
Your phone is registered on a network that has coverage but isn't passing data. Try switching network manually from your phone's settings.

Why would I block a network?
If your main SIM is on Vodafone, for example, blocking Vodafone on your FlexiFone SIM means it only uses EE, O2 and Three. That gives you a real second option when Vodafone is weak.

Does an unsteered SIM work abroad?
Roaming works in 170+ destinations. In some countries (Spain and France, for example) there are typically three of the four operators, and in others only one but still we got you covered while travelling abroad.