The Corrections Department says there will be blanket jamming of cellphones in prisons, once a Telecom tower has been removed from Auckland prison.
The department has been working with telecommunications companies to block cell phone calls in and out of prison.
Inmates were found to be organising crimes, including bringing drugs into prison, using cellphones.
Chief executive Barry Matthews has told the Law and Order Select Committee that all prisons but Auckland now have cellphone jamming technology.
He said a cellphone tower is in the middle of the Auckland Prison, but arrangements have been made to move it.