The Commission for Communications Regulation (ComReg) ruled yesterday that Eircom could not attempt to win back consumers who switch to rivals for three months after they move.

The decision represents an extension of the current one- month exclusion period set for all operators who attempt to contact former customers who switch to other operators. But it is most likely to affect Eircom because it controls more than 80 per cent of the telecoms market.

ComReg made the decision following concerns that there are "serious problems" with competition in the consumer market, where Eircom holds more than 90 per cent market share.

Operators will now not be able to contact former customers or provide them with information about their services for three months after switching firms.

However, the three-month ruling that prevents contact with former customers is significantly shorter than the one-year exclusion that had been sought by Eircom's rivals. They have alleged that the incumbent firm has unfairly targeted former customers who switch networks.

Alto, a lobby group representing Eircom's rivals, said ComReg had failed to grasp the nettle by imposing only a three- month exclusion period. It called on ComReg to monitor Eircom closely over the next few months to make sure it was complying.

However, the Communications Workers Union (CWU) criticised the decision for being too harsh on Eircom by restricting competition in the market. The CWU said it was inconceivable that a restriction on information reaching consumers could be seen as anything other than anti-competitive.

Eircom will be subject to random inspection by ComReg under the new ruling to ensure it follows a new code of practice on "win-back" campaigns. It will also be forced to store all contact with "win-back" customers for verification with the regulator.