Mobile roaming charges within the EU will be significantly cheaper from Saturday when an interim cap comes into effect ahead of a full ban next year.
The cap will make roaming within the EU 75% cheaper during the interim period, the European Commission has said.
From Saturday operators will only be able to charge a small additional amount to domestic prices of up to 0.05 euro (3p) per minute of call made, 0.02 euro (1p) per SMS sent, and 0.05 euro (3p) per MB of data, excluding VAT.
The charges will end altogether on June 15 next year, meaning mobile phone users will pay the same price to make calls, send text messages and use data wherever they are in the EU, as if they were at home.
The new rules aim to prevent consumers receiving huge bills after downloading films or other data while travelling in Europe.
European Commission vice president Andrus Ansip, responsible for the Digital Single Market, said the move was "not only about money, this is about bringing down barriers in the Digital Single Market".
Commissioner Gunther H Oettinger, in charge of the Digital Economy and Society, said the agreement showed that the European Union could deliver tangible results to improve the daily life of Europeans, adding that "roaming charges will be soon old memories".
Consumers have been especially vulnerable to roaming charges since the smartphone market exploded and mobile data consumption soared.
So-called "bill shock" from holidaying in the EU affects more than nine million UK mobile users a year, according to research by comparison website uSwitch.