Consumers signing up for Plusnet's Unlimited Broadband and Calls package can now receive a discount for 12 months.
Previously, cut-price broadband and calls were available on the tariff for nine months, but the offer has been upgraded.
This means customers can pay just £2.99 per month plus line rental for a whole year, and then £9.99 per month plus line rental thereafter.
As such, new Plusnet subscribers joining on an 18-month contract can save £84 during their introductory contract period, as opposed to £63.
Plusnet describes the Unlimited Broadband and Calls package as being "perfect" for large families, downloaders and gamers.
This is because there is no monthly data cap on the broadband deal, which offers up to 16Mb download speeds.
Subscribers also receive a free four-port wireless 'N' router, free activation, Plusnet Protect powered by McAfee, 24/7 customer support and the free help tool Plusnet Assist.
The broadband package comes with Plusnet Weekends - covering calls to UK landlines, 0845 and 0870 numbers.
Subscribers also have the option of an upgrade to Plusnet Anytime for £5 per month, or to Plusnet Anytime International 300 for an extra £7 per month.