
Tiscali was originally looking to raise £600m through a sale.
The future of Tiscali has been uncertain for months as Sky and Carphone Warehouse walked away from negotiations, claiming Tiscali's price was too high.
The Tiscali deal is planned to complete by the end of next month.
Carphone Warehouse said Tiscali customers would continue to receive uninterrupted home phone and broadband services and has created a website at www.talktalk.co.uk/tiscali to give customers information.
The move comes as TalkTalk plans an overhaul of its brand under new marketing director Olivia Streatfeild.