O2 has not yet announced whether it plans to offer its customers a refund over the service outage today.
Pay-as-you-go customers received £10 extra credit and all O2 customers, including those who weren't affected, received a £10 voucher to spend in its retail stores.
More top news
The only way of dealing with British Islamic State fighters in Syria will be to kill them in almost every case, a minister has said.
A settled end to the weekend for many but a damp start to the working week
Liam Fox warned Brussels to put the prosperity of EU citizens ahead of any desire to make the UK pay a price for quitting the bloc.