 Despite this, a few UK networks charge for roaming in Switzerland, the Channel Islands and Isle of Man at the same rates as roaming in the EEA.A special example is Saint Martin, which is part of the EU and has free roaming for EU phones, while in Sint Maarten, the other half of the Caribbean island, prices are high, as it is not part of the EU.On 29 March 2017, the Prime Minister of the United Kingdom, Theresa May's administration invoked Article 50 of the Treaty on the European Union in a letter to the President of the European Council, Donald Tusk, after a majority of British citizens voted to leave the European Union in 2016.