Mobile phone network 3 has abolished roaming charges for its UK customers in seven nations including Italy, Australia and the Republic of Ireland.
3 said it hopes the EU successfully caps roaming charges
Its users will no longer be charged extra for making or receiving calls or texts when visiting the countries.
3 said there would be no one-off fees, and that its users would automatically gain the service.
The other places in which it has abolished the fees are Austria, Hong Kong, Sweden and Denmark.
The firm is able to end roaming fees from the seven nations as each has its own 3 network.
The company confirmed that calls from any of the seven countries back to the UK would come under the user's usual monthly call allowance, and be exactly the same as if they were making a domestic call.
If a user exceeds his or her monthly call allowance when phoning from one of the seven nations they will then be charged a flat fee of 20p a minute.
3 added that its UK customers would also be able to make video calls and access the internet at their usual domestic rate under the new service, which is called 3 Like Home.
European roaming probe
"The launch of the 3 Like Home scheme will significantly benefit our customers as they travel between the 3 group's networks," said 3's Christian Salbaing.
"It underlines our commitment to fair treatment and reasonable pricing for all our customers."
Yet 3's customers will continue to have to pay roaming fees when phoning or receiving calls from other countries.
Mr Salbaing said he hoped the European Commission would stick to its declared intention to cap roaming charges.
The Commission first said in July last year that it intended to enforce a limit on roaming fees, and is continuing to look at the matter.
It said in November that some European mobile phone users were turning off their handsets when abroad because of "excessively high" roaming charges.
3 has more than 3.75 million customers in the UK and more than 13.5 million worldwide.