Here is a guide on how much texts, calls and internet browsing will now cost in the EU and how to avoid those high phone bills.
The European Union has capped the cost of making phone calls, texting or browsing the internet while abroad.
It should be no surprise that David Cameron failed to stop such a long-standing EU figure being nominated as European Commission president.
The EU without the UK is "unimaginable" Germany's finance minister Wolfgang Schaeuble said in an interview with the (£) Financial Times.
He said: "The EU without the UK is absolutely not acceptable, unimaginable. Therefore we have to do everything, so that the interests and the positions of the UK find themselves sufficiently in European politics."
Germany will do everything its power to the UK within the European Union, according to the country's finance minister.
Speaking to the (£) Financial Times, Wolfgang Schaeuble said: "Historically, politically, democratically, culturally, Great Britain is entirely indispensable for Europe."
He added that Britain's exit from the union was "unimaginable."
Shadow chancellor Ed Balls said the Prime Minister's actions in Brussels this week were "catastrophe for Britain and the British national interest."
"We won't be influential in the world, unless we are influential in Europe," he told BBC One's The Andrew Marr Show.
"I've never seen a negotiation so cack-handed," Mr Balls said about David Cameron's failure to stop the appointment of Jean-Claude Juncker as the new head of the European Commission.
Mr Balls said about the Prime Minister: "He's weak, he's lost control, he's on the back foot, Britain is suffering. I think it's catastrophic for Britain."
David Cameron is following in the footsteps of Harold Wilson on Europe, former Conservative Chancellor Lord Nigel Lawson has said, after the Prime Minister failed to halt the appointment of Jean-Claude Juncker to the European Union's top job.
Speaking to the Independent on Sunday, Lord Lawson said: "He might do a Harold Wilson – whether the public will believe it as they did in 1975 is another matter [...] he was going to renegotiate the terms and then put it to the people in a referendum".
"Through the long renegotiation, we got absolutely damn all [...] but he presented it as a great success, and people bought it. I think David Cameron could try to do the same; he will get very little and he will present it as something", he said.
He added: "If David Cameron had said, 'Well I'm not sure how to vote, it depends on what I am able to negotiate' – that would have been a stronger hand. But he's actually made it clear he's going to vote for 'in' irrespective, so he has no negotiating hand to speak of."
The leader of Britain's biggest business group has said that the country's economic success depends on it remaining a full member of the EU, after senior Tories revealed that more than 150 of the party's MPs would campaign to leave the union in a referendum.
CBI director general John Cridland told the Observer that full membership of the EU boosted British jobs, growth and investment.
"The EU is our biggest export market and remains fundamental to our economic future," he said. "Our membership supports jobs, drives growth and boosts our international competitiveness."
David Cameron's failure to block the appointment of Jean-Claude Juncker to the European Union's top job shows he poses a "real and present danger" to the British economy, Ed Miliband has claimed.
Writing for the Sunday Times (£), Mr Miliband claimed that Mr Cameron had demonstrated that he "is incapable of reforming Europe".
"Mr Cameron blusters about bullying 27 other member states into agreeing fundamental treaty change before a referendum on withdrawal. But the isolation he achieved this week is not 'splendid'", he wrote.
"It shows he is incapable of reforming Europe and his strategy of getting change by making threats to leave to get change does not work".
Health Secretary Jeremy Hunt accused European leaders of "cowardice" after they privately voiced concerns of the nomination of Jean-Claude Juncker but voted for him at a summit in Brussels
Jean-Claude Juncker is the "living manifestation" of the ability of small states to have an influence in the European Union, according to Scottish First Minister Alex Salmond.
He said: "The fact that Mr Juncker has been Prime Minister of Luxembourg - the smallest country in the EU with a population the size of the city of Edinburgh - rather defeats the argument that all of the big jobs go to the big countries."
He added: "Clearly Mr Juncker is a living manifestation that another one of the unionist arguments bites the dust."
Mr Juncker's "sensible" statements on Scottish independence, when he suggested that the EU should keep out of the debate, had also been welcomed by the Scottish National Party, he said.
Health Secretary Jeremy Hunt condemned the European leaders who privately voiced concerns of the nomination of Jean-Claude Juncker but voted for him at a summit in Brussels, as cowards.
He told Sky News: "As a result of cowardice yesterday from other leaders who were not prepared to stand up in public and say the things they said in private, they're going to have to work a lot harder to persuade the British people that Europe can be trusted with a proper reform agenda."
David Cameron has "let Britain down" after failing to stop Jean-Claude Juncker from taking the European commission president job, shadow foreign secretary Douglas Alexander said.
– Douglas Alexander, shadow Foreign Secretary
There is nothing splendid about David Cameron's isolation today. His defeat has diminished and not enhanced his standing on the international stage.
He badly misjudged these negotiations and as a result has let Britain down. Europe needs to change, but the Prime Minister made a series of unforced and unnecessary errors.
Any pretence that the Prime Minister could convince 27 other European leaders to accept his wholesale redesign of the European Union has been stripped away by his defeat.