T-Mobile UK parent Deutsche Telekom is reportedly in talks with Vodafone, France Telecom and Telefonica about selling its British unit.
The Financial Times has reported that the three companies had shown interest in the network, although talks are said to be at a preliminary stage.
Company representatives did not comment.
Analysts have said that a deal could potentially be blocked by regulators as a theoretical combined entity could control around 40 per cent of the UK market.
Deutsche Telekom hired US bank JP Morgan Chase in July to advise on its strategic options for T-Mobile, which had an estimated enterprise value of around €4 billion at that time.