It’s been revealed work on a back-up system for Victoria’s crisis-addled triple-0 call system is yet to begin, despite being flagged as “critical” nine months ago.

The operator of the system, Emergency Services Telecommunications Authority (ESTA), concedes without the back up system, a worst case scenario of a main system failure could lead to multiple deaths.

The Herald Sun has revealed a tender process began to build the back up to the computer-aided dispatch system in July last year.

But nine months on, work is yet to begin.

A dozen lives have been lost since then amid major delays in calls getting through to triple-0

Former police chief Graham Ashton is expected to deliver his review into the system last month while the Inspector General for emergency management is also conducting a review.

The government has announced it will add an additional 120 Triple-0 operators to help the struggling system.