Virgin Media suggested way back in March that it may adopt a "three strikes and you're out" policy towards internet subscribers who illegal download copyrighted material.
Well the company is now taking action.
From next week, for 10 weeks, customers who download music from illegal file sharing websites will receive a written warning from Virgin Media.
The ISP is working with the British Phonographic Industry, a body that represents music labels in the UK, and has been fighting websites which it claims are damaging legal music sales.
The BPI has publicly attacked ISPs which do not want to police their customers' downloads - most recently the Carphone Warehouse.
However, Vigin Media has co-operated although stopped short of threatening its 3.5 million customers with disconnection.
It said in a statement that it hopes the letters will "educate" its customers - liable to be parents who have no idea of what teir kids are actually downloading.
However, with each Virgin letter will be send one from the BPI, which warns that persistent offenders could be disconnected or taken to court.
A Virgin spokesman told The Telegraph: "We want people to enjoy music online without infringing the rights of musicians and music companies. This campaign is about helping our customers understand how they can do this".