Prisoners will soon have access to an anonymous tip-off line so they can dob in criminals or suspicious behaviour to police.
The Crimestoppers phone line has received almost 4000 phone calls from the public since it was launched in October last year.
From 21 June, inmates will be also be able to call Crimestoppers for free from a prison payphone. The Corrections Department says it will not be monitoring the calls.
It says prisoners have plenty of knowledge about crime and criminals but often do not speak up for fear of being branded narks.
Crimestoppers says more than half its calls relate to drugs, and about 1500 have given police enough information to take action.