TalkTalk broadband and home phone subscribers can now save money on the firm's SIM-only plans.
Existing TalkTalk customers can get their hands on mobile minutes, texts and data from just £5 per month, without the need to buy a new phone.
TalkTalk is offering a £2.50 discount on each of its SIM-only plans - Small, Medium and Large - when customers use the 'SIMOFFER' voucher code.
Subscribers receive double the mobile data when they sign up over the internet.
The Small tariff offers 300 minutes, unlimited texts and 600MB for £5 per month to online customers, while Medium offers 500 minutes, unlimited texts and 1GB of data for £7.50 per month.
Customers signing up for the Large SIM-only plan online receive 2,000 minutes, unlimited texts and 4GB of data for £17.50 per month.
TalkTalk is also offering £2.50 per month off its short-term plans, which require just a one-month commitment. These are available from just £7.50 per month.
Dan Meader, Mobile Director at TalkTalk, explained that the firm's SIM-only plans include "built-in savings features" which help customers keep their bills down.
These include free calls between TalkTalk mobile phones on the same account, free text alerts and voicemail services, and free calls to TalkTalk's customer care team.
Subscribers can also make calls from their TalkTalk mobile to their home phone without incurring any charge.
"If you’re coming towards the end of your contract and you’re still happy with your old mobile, as a TalkTalk customer you can save a bundle," Mr Meader stated.
He explained that TalkTalk customers can simply insert their new SIM card to their handset and then switch their number over.