Rules on 'portability' mean mobile users may not know if extra charges are incurred when calling a number in a rival network, writes John Downes

Vodafone customers face uncertainty about the cost of using their phones, following the recent implementation of new rules forcing mobile phone network providers to allow consumers retain their mobile numbers when switching networks.

The move, introduced by the Commission for Communications Regulation (ComReg) to increase competition in the sector, has led to a high-profile campaign from mobile phone companies outlining the "portability" of their mobile numbers.

However, where before a customer calling a number in a rival network would be aware of any extra charges this would incur - the prefix would be different - under the new system this is no longer possible.

While some mobile phone companies have sought to introduce measures to counteract uncertainty among customers about the price of their call, the market leader, Vodafone, has no such system in place at present.

O2 currently provides a recorded announcement letting customers know if the person they are telephoning is no longer an O2 customer, while Meteor offer a free text-message service, allowing customers to ascertain the network before placing a call.

A spokesperson for Vodafone said: "Up until a few weeks ago, our concentration was on implementing the porting process. However, we do recognise that we have an obligation to inform customers."

"This is going to be available in the very near future in the form of an on-net beep informing you when you dial whether you are dialling another Vodafone customer. We are fully focused at the moment in terms of delivering it to customers very shortly."

The failure of Vodafone to introduce such a system, particularly in light of recent revelations that the company's Irish subscribers pay some €146 million more in annual bills than their British counterparts, came in for criticism from the Consumers' Association of Ireland.

It's chief executive, Mr Dermott Jewell, said: "I would think by now that it should have been installed by all in tandem with the changeover. That it is not, is poor. In this day and age, it reflects badly on one of the highest technologically-based-systems we have.

"I can ring anywhere, but I can't know how much I'm paying." Charges for calling other networks vary, depending on the service provider and the tariff option chosen, with so-called "pay-as-you-go" customers paying up to 65 cents a minute for calls to other networks.

Allowing customers to bring their numbers with them when they change networks has necessitated significant capital investment from mobile network providers, with 0₂ and Vodafone estimating they have invested approximately €10 million each.

Meteor, the smallest operator in the market, estimates its investment at around a third of this figure.

The changeover to Mobile Number Portability came into effect on July 25th with the aim of enabling consumers to move between networks without incurring the additional cost and inconvenience of a number change. Small businesses, in particular, were believed to be most likely to benefit from the move.

At the time, Ms Etain Doyle, ComReg chairwoman, said: "ComReg, working with industry, has sought to facilitate consumer choice in the mobile market with a fast and consumer-friendly porting solution. International experience would suggest that Mobile Number Portability can have a significant impact on both consumer behaviour and competition in the mobile market."