The advice to favour oldfashioned technology over the newer variety is one of several tips that will be included in a consumer guide to mobile use abroad to be published by the regulator this month.

The guide, which will anger mobile operators such as Vodafone, Orange and O2, is also likely to prompt accusations that the regulator is washing its hands of the problem of high mobile call costs abroad rather than tackling it.

Despite constant criticism of providers by consumer groups and MPs over the cost of mobile calls from abroad, research by the European Commission has found that UK consumers still pay some of the highest charges to call home.

A British holidaymaker in Italy typically pays £3.99 for a four-minute call home, compared with £2.71 for a French tourist in Italy and £2.62 for a German. The discrepancy in the cost of receiving a call is even greater.

Mobile operators consistently maintain that the high cost results from the charges they have to pay for arrangements with local network operators.

Ofcom denied that it was wriggling out of addressing high call charges. It said that the guide formed part of its effort to comply with a request from the Commission to “raise awareness” among British consumers of the costs of making mobile calls abroad. It emphasised that formal efforts were also under way to investigate the costs of mobile call charges abroad and to tackle any problems. Vivane Reding, the Information Commissioner, warned mobile companies last year that progress on bringing down call charges was “both necessary and possible”.

The European Regulators Group, a body of 32 European telecoms regulators including Ofcom, are also investigating the prices operators charge each other for handling calls abroad.

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