Ofcom is introducing minimum performance standards for Openreach, the company responsible for managing and maintaining BT's broadband network.
Under draft decisions which have been notified to the European Commission, the vast majority of phone and broadband faults will have to be repaired within two working days.
Additionally, most customers wanting a new line must receive an appointment within 12 working days.
Ofcom's new targets are expected to apply to Openreach from summer 2014, with sanctions - including fines - possible if the firm fails to meet them.
"The new targets are designed to ensure better service for telephone and broadband customers in future," the media regulator stated.
Ofcom said it will monitor Openreach’s performance "closely" and intervene further if required.
The network operator will be required to report publicly on its performance, ensuring further accountability and transparency.
Meanwhile, Ofcom has announced new measures geared at boosting super-fast broadband competition in the UK.
A number of different broadband providers sell super-fast services over BT’s network, with 2.7 million packages delivered in this way.
At present, if a consumer wishes to change super-fast broadband provider, the company they are switching to must pay £50 to Openreach.
This is often passed on to the customer, meaning they are required to pay a connection fee for fibre services.
However, Ofcom intends to cut the wholesale fee to £11, which should enable broadband providers to reduce start-up costs for new customers.