Is O2 and EE the same network?

Re: EE Mobile Phone We do advise anyone with an EE handset to get it unlocked as we can’t guarantee the plusnet mobile SIM will work in the device . We do use the EE network, however operate as a separate entity.

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.