Who uses Vodafone network

In all honesty you can put a BT sim into a locked EE phone and it will still work .

Networks like BT Mobile, Plusnet Mobile and 1pMobile piggyback on EE’s network for coverage. It isn’t necessary to be an EE customer to get coverage from EE on your mobile phone. This is because a number of other mobile networks also offer EE coverage.25 Mar 2021

Asda Mobile is a mobile virtual network operator, which means that instead of running its own network, it ‘piggybacks’ off another networks. So far, it’s used EE’s signal , but it’s switching to Vodafone in September.