Tiscali's broadband users are being urged to upgrade to TalkTalk's phone line rental service.
ISPreview.co.uk reports that any broadband-only subscribers who do not switch to services provided by Tiscali's new owner will see £5 added onto their bill.
For customers currently paying £14.99 per month, this would see the cost of their broadband package rise to £19.99.
TalkTalk, the telecommunications arm of Carphone Warehouse, says migration from Tiscali services will commence on January 7th 2010.
Justifying the action, the firm says its phone line offers better value for money and a higher service quality than Tiscali customers currently receive.
Earlier this month, TalkTalk announced plans to raise its standard UK network connection speeds from January.
The firm announced that 24Mb downloads will be available in the new year as it continues to invest million in its next-generation broadband infrastructure.