Customers caught up by the O2 data network crash are to receive millions of pounds in total compensation.
O2 has said that the software issue that left millions of customers unable to use any data services worldwide yesterday was down to a flaw in Ericsson certificates.
Those on pay as you go will get 10 per cent off their first top up in the new year or 10 per cent off data for mobile broadband devices.
Guidance from regulator Ofcom said that, depending on circumstances, it "may be appropriate" for mobile networks to offer some form of compensation for loss of service.
In a statement, Ericsson said that Thursday's major data network outage had been caused by an issue with its software.
O2, Britain's second biggest network, and Japan's Softbank, both Ericsson customers, reported outages on their 4G networks earlier on Thursday.
'We will be updating our customers later today on how we will make yesterday's data service issue up to them and we'd once again like to thank our customers for their patience'.
If customers are not happy with how a complaint has been responded to, or it takes more than eight weeks to be resolved, a further complaint can be submitted to an independent Alternative Dispute Resolution (ADR) scheme.
O2 has announced it is to carry out a full review into the technical fault.
"We fully appreciate it's been a poor experience and we are really sorry".
"I want to let our customers know how sorry I am for the impact our network data issue has had on them, and reassure them that our teams, together with Ericsson, are doing everything we can", Mark Evans, CEO of Telefonica (O2) United Kingdom, said.
Ericsson, which builds most of the backend tech for the majority of cellular network providers, said the downtime was caused by an expired certificated in a version of its management software that some EU-based telecommunications companies use.
This also affected customers of Giffgaff, Lycamobile, Sky and Tesco, who use O2's network.
She added: "Ericsson sincerely apologises to customers for the inconvenience caused".
According to Marielle Lindgren, CEO Ericsson UK & Ireland, the cause of the problem was in certain nodes in the core network "resulting in network disturbances for a limited number of customers across the world, including in the UK".