A review of police call handling has made 30 recommendations for improvements to be addressed "as a priority", after finding a number of weaknesses in the new system.
Her Majesty's Inspectorate of Constabulary in Scotland (HMICS) was tasked with carrying out the urgent review following the deaths of John Yuill and Lamara Bell in July.
The couple lay undiscovered for days after a crash on the M9 near Stirling despite a sighting of their wrecked car being reported to a police control room.
The HMICS review was ordered by the Scottish Government.
It has reported weaknesses in Police Scotland's approach to implementing its new national call handling system, which has seen a number of control rooms closed.
HM Inspector of Constabulary Derek Penman said: "The oversight of this project has been inadequate with key risks and other issues not being identified or highlighted to senior managers.
"There was an initial focus on meeting deadlines and increased productivity rather than a well-managed project with a focus on customer service, good staff relations and thorough process design."
An HMICS audit of calls provided assurance over the accuracy of information being recorded on systems, but it also highlighted inconsistencies in the way incidents are handled.
It found examples of call handlers being under pressure to end calls quickly and grading of calls being dependent on resources available.
HMICS also found that some staff noted information on scribble pads rather than inputting it directly on to the system, although Police Scotland has recently introduced processes to monitor and manage this.
Mr Penman said staffing levels at Bilston Glen - where the call regarding the M9 crash was received - were insufficient and had resulted in poor call handling performance, although the force has made "considerable efforts to address this".
In an interim report published in September, HMICS urged Police Scotland to suspend the planned closure of call centres in the north and keep them fully staffed until a new area control room is fully operational.
Remaining personnel in the understaffed Aberdeen, Inverness and Dundee call centres are facing ''unacceptably high'' pressures and the practice of diverting overflow calls to the central belt control rooms at Bilston Glen and Govan is creating additional risk to the public, the watchdog concluded.
Its interim recommendation stated that ''the service centres in Dundee, Aberdeen and Inverness should be maintained and staffed appropriately'' until a planned new area control room in Dundee is fully operational.
Scottish Justice Secretary Michael Matheson accepted the recommendation, and announced £1.4 million of funding to recruit and retain call handling staff.
Today's full report makes it clear that the Scottish Police Authority should not approve any further stages of the call handing project until it receives independent assurance that Police Scotland is ready.
Its 30 recommendations include the appointment of "an experienced and qualified programme manager with immediate effect" to manage the remaining stages of the new call handling model, an urgent review and strengthening of the approach to programme governance, and improved financial management and reporting for the call handling project.
Police Scotland should also promote an "improvement culture" where staff are encouraged to report adverse incidents or "near misses", and introduce processes as soon as possible where these can be recorded, assessed and any improvement identified and implemented.
The review focused broadly on all call handling procedures and was ordered in addition to the continuing independent inquiry specifically into the M9 incident by the Police Investigations and Review Commissioner.
Mr Matheson will make a statement to the Scottish Parliament later detailing the Government's response to the review's findings.