Oftel has published advice for different groups of users: those who commute daily, regular visitors and holidaymakers.

Oftel found that a daily commuter to the Republic can save 40 per cent on roaming costs by switching from a pre-pay tariff to a monthly contract. By using a different SIM card, a commuter using a pre-pay phone can save over 70 per cent.

Many people in Northern Ireland are still unaware of the higher costs of using their mobile phone abroad. Key findings of joint research with the Republic of Ireland regulator ODTR on international roaming are:

• · A third of consumers are still unaware that they can be charged for incoming calls – up to £1.50 per minute – when using their phone in Ireland;
· 80 per cent of consumers do not believe that the prices for using their mobile phone in Ireland represent value for money;
· Less than half of consumers have tried to reduce their mobile bills when in Ireland, either by using text messages or switching from a pre-pay to post-pay service which can give savings on roaming charges of over 50 per cent.

"Oftel has been working with ODTR, the Irish regulator, to highlight the costs to UK consumers of using their mobile phone in the Republic of Ireland.

"This research has shown that consumers in Northern Ireland can halve the cost of using their mobile phone in the Republic of Ireland by taking a number of simple steps.

"Although savings will depend on individual consumers’ use of their mobiles, visitors could save over 50 per cent on their roaming costs by switching from pre-pay to contract tariff.

"For regular travellers, buying an Irish SIM card for use while in Ireland could save over 50 per cent for contract customers or around 70 per cent for pre-pay customers.

"Selecting a different Irish network to roam on is another option: the different between the cheapest and most expensive network can be up to 18 per cent.

"Oftel will continue to work with NIACT and with ODTR to address the problem reported by Northern Ireland consumers living in border areas who find their phone may pick up a signal from the Republic of Ireland even when they are still in Northern Ireland."

David Edmonds said that Oftel has published advice on how consumers can reduce their phone bill when using their mobile phone abroad:

"Wherever your destination, there may be ways of saving money while you are using your phone outside Northern Ireland.

"Think twice before making a call if you can send a quick message instead as sending a text message is cheaper than making a one-minute call. "Think about changing from pre-pay to contract. If you are a regular traveller, the money you save on cheaper calls may even pay for the line rental charge. "Check with your network to see if it offers an international traveller service, which gives you cheaper calls abroad for additional line rental and may offer a good deal for heavy users. "And before you travel, check with your network so you know exactly how much you will be charged for using your phone." Commenting on the joint project with the Irish regulator ODTR, David Edmonds said: "Oftel has worked together with the Irish regulator, ODTR, and I am pleased to see the start of a working relationship that will bring benefits to both regulators in the future. "This is an example of the kind co-operation that will become increasingly important under the new European Directives. "ODTR will be publishing research and advice for consumers in the Republic of Ireland."