(Telecompaper) A group of telecoms companies have written to Ofcom to demand the introduction of a cap on the amount of spectrum that a single mobile operator can own, reports the FT. The chief executives of TalkTalk, CityFibre, PCCW-owned Relish and the Federation of Commununications Services have signed a letter asking for a 30 percent cap, a limit already exceeded by BT with its ownership of the EE network. The news follows a similar move from 3 UK CEO Dave Dyson, who in September had renewed calls for Ofcom to rebalance the distribution of mobile spectrum, enforcing an ownership cap as part of the upcoming 2.3-3.4 GHz spectrum auction.