BARCELONA, Feb 26 (Reuters) - A clash between Big Tech and European Union telecoms firms over who will underwrite network infrastructure is set to dominate discussion at the world's largest telecoms conference this week. More than 80,000 people, including tech executives, innovators, and regulators, are set to descend on this year's Mobile World Congress (MWC) in Barcelona. EU industry chief Thierry Breton on Thursday launched a 12-week consultation on its "fair share" proposals, under which Big Tech platforms would bear more of the costs of the systems which give them access to consumers. By contrast, Deutsche Telekom (DTEGn.DE), Orange (ORAN.PA), Telefonica (TEF.MC) and Telecom Italia (TLIT.MI) have been actively lobbying for Big Tech to pay the fees. "This discussion around 'fair share', or what we sometimes call the 'investment gap', is going to be a threshold question," said John Giusti, GSMA's chief regulatory officer.

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