With the European Commission set to make networks charge local rates, Europe's mobile companies face a revenue drop of up to 60% from calls made by their customers overseas. That's equivalent to a hefty 10bn a year.

None of the Irish operators will say how much they earn from roaming. Both O2 and Vodafone Ireland said such information was "commercially sensitive". But the figures are big.

European mobile operators generate between 10% and 20% of their revenue from roaming fees, reckons Stefano Nicoletti, of panEuropean telecoms consultancy Ovum. In an Irish context that would put Vodafone's roaming revenue last year anywhere between 120m and 240m.

Irish people travelling abroad can pay over 2 a minute for calls in some countries, depending on the network. If the European Commission abolishes this, operators such as Vodafone and O2 will be under pressure to come up with alternative sources of revenue.

Expect a marketing deluge around alternative services.

Vodafone recently began a television campaign advertising 'football highlights, anywhere' to Irish customers who sign up for its 3G service, a new network that enables more information to be sent and received by phones at high speeds. O2, meanwhile, has been promoting its iMode service, promising "internet access on your mobile".

The Irish networks are downplaying the potential revenue hit. O2, Vodafone and 3 Ireland recently dropped roaming charges for customers travelling to the UK, and argue that this market accounts for the bulk of roaming revenue. They say they don't anticipate much more of a hit from the new proposals.

Nonetheless, they will look to their bottom line. "The main place that they have where mobile operators can potentially make it up is in data services and 3G, " said Merrion Stockbrokers' analyst Brid White.

Given the booming Irish economy, she also forecasts that the mobile operators will be in no rush to drop Irish prices. The signs are there.

Last week, for instance, Vodafone UK announced an agreement with music labels and content providers to drop its data charges. This means cheaper downloads for British customers, but Vodafone said it had "no plans to replicate" the lower data pricing model in Ireland.

The networks are fond of countering allegations of high Irish charges with the response that Irish people talk and text more. Now, presumably, the hope is they will download more too.