The deal will see the two companies build a communications platform that seamlessly switches between private mobile radio networks, Telstra's Trunked Radio network, Wi-Fi networks, Satellite networks and Telstra's Next G mobile data network.
Telstra will provide the networking technology, NEC the in-car hardware.
Some 167 field staff work for the Victorian Sherriff's Office, faced with the often arduous task of delivering warrants and court actions.
At present the Sheriffs communicate back to base with UHF and SMR radio technologies but have no means of switching between the two.
The new system will seamlessly switch between the different networks depending on technical and environmental factors.
A spokesperson for the Victorian Department of Justice said cost is not as larger consideration as the safety of Sheriffs Office staff.
The system will also be used to track the location of Sheriffs Office vehicles via GPS.
Asked if staff had given permission for their location to be tracked, the spokesperson for Justice said GPS technology is "widely used by both public and private sector organisations as a means of improving employee safety."
"As with all safety matters, due consultation is required and the department accepts all responsibilities to consult on this... under the Act."