An MNO (Mobile Network Operator) is a carrier that owns the actual towers, spectrum and core network kit. In the UK there are four MNOs: EE, Vodafone, Three and O2.
MNO vs MVNO
- MNO: owns the network. Examples: EE, Vodafone, Three, O2.
- MVNO: rents capacity from an MNO. Examples: giffgaff (O2), VOXI (Vodafone), SMARTY (Three).
Most "alternative" UK providers are MVNOs sat on top of one of the four MNOs.
Why it matters
When you sign up to a single-network provider — MNO or MVNO — your coverage depends entirely on that one network. Multi-network providers like Fuse use all four MNOs and switch automatically to whichever has the strongest signal where you are.