Britain’s four biggest mobile phone operators used their own industry trade body as a forum for colluding to shut rival 3 out of the UK market, the High Court heard yesterday.

Lawyers for 3 levelled the accusation against top executives at O2, Orange, Vodafone and T-Mobile in the opening gambit of a £250 million claim against the four companies — the largest competition action of its kind to reach the UK courts.

Jonathan Sumption, QC, acting for 3, alleged that the other four firms also abused their dominant position in the market by using the five-day hand-over period for porting personal phone numbers in order to stitch together special retention packages for customers who try to leave their networks.

Modern systems of number porting used in other EU countries have for several years allowed users to take their numbers with them within hours of joining a new operator.

All five mobile phone operators used to meet as members of the Operator Steering Group (OSG), a self-regulating industry body whose purpose is to improve the functioning of mobile networks, rather than agreeing on operators’ commercial objectives — a move that could be deemed anti-competitive.

But twice in 2005 the four largest operators outvoted 3 by four votes to one to keep the system of number porting to a five-day process.

Mr Sumption told the High Court: “The inference to be drawn is that the resistance [to portability] has been concerted.”

Mr Sumption later read out the minutes of a meeting on October 27, 2005, kept by the 3 representative, who noted: “Simon Whittle of O2 said the industry is all about retention at the moment.”

Nicholas Green, QC, acting for O2, dismissed 3’s application as “pleadable piffle” and said it “should be struck out”.

The case continues.

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