Northern Territory authorities lost contact with 85 criminals wearing electronic ankle tags for up to four days after a key part of Telstra's network dropped out.
The outage that affected the network's mobile G4S service on May 4 meant that Correctional Services officials had problems keeping track of where the offenders were in the community.
"At 8.10am May 4 there were approximately 85 electronic monitoring devices identified as having an unresolved communication issues," an NT Corrections spokesman told the NT News on Tuesday.
"By 11.30am, 23 had been resolved. By Saturday May 5, seven remained unresolved."
The spokesman said the monitoring devices were all finally restored by May 8.
The department's website says the electronic tags are used to monitor offenders whose movements are restricted, including those on home detention, or who are not allowed to go to certain places such as a park or school.
The devices use Global Positioning Satellite (GPS) technology to help authorities monitor the location of offenders.
At the time, Telstra said outages to its services had been caused by damage to a fibre link after a cable pit in NSW's central west was hit by lightning.
The damage caused some triple-zero calls to drop out for 10 hours across five states.
Meanwhile, Telstra says it has fixed its 4G mobile services after a nationwide disruption on Monday.
Comment is being sought from Telstra and the NT's Department of Correctional Services.