The $5 million cellphone jammers installed in prisons appear to have glitches, with the new 2degrees network being used to connect people behind bars.
The Government spent $5m to $6m installing the technology, which was supposed to block all cellphone calls in New Zealand's 20 prisons from February 2009. It costs a further $200,000 a year to maintain.
However, a prisoner told the Parole Board recently how he used the 2degrees network to call his children.
And last month four cellphones were found thrown into Auckland's maximum-security prison Paremoremo.
Prisoners have been known to use cellphones in the past to organise drug deals and plot escapes.
A spokeswoman for 2degrees said the company had worked with Corrections to make sure its spectrum was jammed in all prisons and it was not aware of any problems.
When asked whether 2degrees, or any other network, could be used in any prisons, Corrections would not answer "for security reasons".
Beven Hanlon, president of the prison guards' union the Corrections Association, said the fact that people were trying to smuggle phones into prisons suggested that the phones were still working.
Alcohol and drug counsellor Roger Brooking, who was at the Parole Board hearing when the man was being questioned, said he later asked the man how he was using a cellphone when they were supposed to be blocked.
He was told the 2degrees network worked in Rimutaka and said the money spent on seemingly ineffective cellphone jammers would have been better spent on rehabilitation.
Corrections would not say whether the 2degrees network had now been blocked but said the jammers were being upgraded to cover technological advances as they occurred.
"Blocking the new 2degrees network is part of that process," Derek Lyons of Corrections said.
He would not say whether all networks were blocked at all prisons, citing security reasons.
Anecdotally, criminal activity in prisons had fallen since the jammers were introduced because prisoners were forced to use pay phones, which were monitored, he said.
The phones being found in prisons had generally been on site since before the jammers were introduced.
The jammers send out inteference, with the networks' permission, to block cellphone signals. The blockers use white noise to give blanket coverage inside a prison's walls.
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