Carphone Warehouse has not confirmed a bid, but reports say it has offered £450m for the firm. Tiscali put the business on sale earlier this year.
Tiscali wanted to dispose of its UK assets by June 2008, but it missed its deadline.
Italian broadband provider Fastweb - owned by Swisscom - is another mooted buyer for Tiscali's UK business.
If it did acquire the Tiscali UK assets, Carphone would add them to its growing TalkTalk broadband and voice call business and the AOL broadband operation it also controls.
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