We run on the O2 network, so 4G coverage is standard.

Which carrier does giffgaff use?

Giffgaff uses the O2 network. Giffgaff is a 'virtual' provider, which means it uses another provider's infrastructure – in this case O2's. It offers 3G, 4G and 5G coverage.

What network is the same as giffgaff?

Giffgaff's coverage relies on O2's, which means it's currently at around 99% 4G population coverage indoors. That puts it behind Three and EE and in line with Vodafone. Giffgaff also has strong 3G and 2G coverage, so you should be able to get mobile data of some kind almost everywhere.