Vodafone and Telefonica are both reported to have made offers of around £4 billion for T-Mobile UK.
Additionally, T-Mobile parent Deutsche Telekom is reported to be considering a joint venture instead of a sale, and is said to have held talks with France Telecom about a possible merger with Orange UK.
Deutsche’s other option is to keep the business and undertake a full restructure.
Analysts have suggested that the successful buyer of T-Mobile UK would then be in a good position to attract the exclusive Apple iPhone deal away from O2.
Neither party has commented, but a decision is expected to be made soon.