Inadvertent mobile roaming could be costing people in border areas as much as £11m per year, according to new research published by Ofcom, and carried out in part, in Fermanagh.

Here, 72% of people surveyed said they had experienced the problem, and 56% said they were affected by it at least once a week.

The research forms part of Ofcom's Communications Market Report for Northern Ireland which examines the availability, take-up and usage of internet, telecommunications and broadcasting services.

Ofcom commissioned research into mobile roaming in order to identify the extent of the problem and to try put a figure on the additional cost to consumers of making and receiving calls on Republic of Ireland networks without having crossed the border.

The research surveyed people in cities, towns and villages along the entire length of the border, and included interviews with mobile users in Garrison, Belcoo, Roslea, Enniskillen, Derrylin, Pettigo, Belleek, and Newtownbutler.

In Fermanagh, 72% of people surveyed said they had experienced the problem, and 56% of people said they were affected by it at least once a week.

The research suggested that an estimated 74% of users in Northern Ireland's border regions (approximately 105,000 people) experience this problem.

Based on the overall findings, Ofcom estimates that 10 million calls per year are made whilst inadvertently roaming at an estimated extra cost to consumers of £10.9m per year (based on an average call length of two minutes). This means that the problem may cost the 105,000 people living in affected areas as much as an extra £100 a year each on their mobile phone bills.

An estimated 85% of those people affected were aware of the problem. but 80% were not aware of how they could avoid additional costs, such as requesting special network tariffs from their operators – just seven per cent of those in affected areas have done this – or locking their phone onto just one network.

Denis Wolinski, Ofcom's Director for Northern Ireland said the research showed that inadvertent mobile roaming was still a very real issue for mobile phone users in border areas.

"We recognise that operators have introduced new tariffs to reduce the cost of inadvertent roaming, but the message doesn't appear to be getting through to customers.

"For example, 69% of mobile users along the border are O2 customers and O2 has an Ireland Bolt On costing £1.99 a month, or 50p a week, which allows users to roam onto any Republic of Ireland network but only pay their standard domestic rate. People just do not seem to know about the special tariffs that are available, and I would recommend anyone who is affected by the problem to ask their mobile provider what they can offer.

He said Ofcom welcomed the European Parliament ruling to impose caps on roaming prices across Europe.

"This is a very good result for consumers who can expect savings of 50-60% on what they were paying a couple of years ago."