Free data roaming will continue even if the UK leaves the EU without a deal, Brexit Secretary Dominic Raab has said.
He said two mobile operators had agreed and if others did not follow suit the government would force them by law.
Mr Raab also said the UK would not pay the full £39bn divorce bill if the UK fails to reach a deal with Brussels.
The cabinet is meeting for a three-hour "no deal" planning session and is ready to publish contingency plans for driving licences and passports.
Extra charges for people using their phones in another EU country were scrapped in June 2017. But the EU regulation banning them will not automatically be part of UK law after Brexit on 29 March next year.
In theory this means UK mobile operators, if they want to, could reintroduce the charges that could make it expensive to use a mobile phone in another EU country.
Mr Raab told BBC Radio 4’s Today programme two mobile operators, Vodafone and EE, had publicly agreed not to bring them back for British citizens.
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He said the government was aiming to get a Brexit deal with Brussels by mid-November at the latest but was stepping up contingency planning in case that did not happen.
He said one of the consequences of a "no deal" Brexit "is that obviously we wouldn’t pay out the money that has been agreed as part of the withdrawal agreement".
The UK would "recognise our strict legal obligations" but that the amount paid would be "significantly, substantially lower" than the £39bn agreed with the EU.
Last month the government published 24 no-deal documents covering industries including medicine, finance and farming. There were warnings of extra paperwork at borders and extra credit card charges for Britons visiting the EU.
Mr Raab said Thursday’s 28 documents "range from protecting consumers from mobile phone roaming charges to upholding environmental standards".
Mr Raab said the no-deal plans were "not something we want to have to implement".
"No one should pretend that ‘no deal’ would be straightforward," he said.
"There would be risks and some short-term disruption. Extra checks at the EU border would bring delays for businesses."
And trading with the EU on World Trade Organization terms – an outcome backed by a group of Brexiteers in a report this week – would be "inferior" to the current arrangements, he said.
But Mr Raab also criticised those he said were "scaremongering for political ends" about no deal being reached.
"It’s nonsense to claim that UK supermarkets would run out of food," he said, adding that people should not be scared by the government’s request to pharmaceutical companies to stockpile extra medicine supplies.
More no-deal publications are expected in the coming weeks.