Volunteers and Army personnel are expected to be drafted in as 999 cover for West Midlands ambulance crews who are to go on strike next week.
Union officials yesterday confirmed that industrial action, including a work-to-rule and strikes, sparked by a pay dispute will start next Wednesday.
As well as an overtime ban, working to rule and refusing to cover any sporting events, paramedics and technicians will stage three two-hour walk-outs from 7am on February 9, 16 and 23.
More than 90 per cent of crews in the West Midlands and Shropshire ambulance services - 730 of about 800 paramedics and technicians - are expected to support the move.
Representatives from the Association of Professional Ambulance Personnel (APAP), Transport and General Workers' Union, the GMB and Unison will meet trust bosses for more "crunch" talks tomorrow in Dudley.
The unions and employers have been at loggerheads since, it was claimed, the Department of Health interfered with a pay deal - negotiated under the NHS Agenda For Change - agreed with ambulance services in Shropshire and the West Midlands in July.
The deal would have seen technicians' pay rise from £20,000 to £24,000 and paramedics' salary increase from £21,000 to between £22,000 and £30,000.
However, under a new system preferred by the employers, technicians would face a £1,500 pay cut, with paramedics seeing no change in their pay.
Ray Salmon, Unison's regional organiser, said: "We are still available 24/7 for further negotiations to bring this situation to an end because as far as our members were concerned, industrial action was only ever a last resort. However we feel we've now been forced to take action.
"However, if there is a major incident, such as a plane crash, all bets are off and everyone will be called into cover - otherwise this will continue indefinitely."
In December, the Department of Health put St John Ambulance and Red Cross on stand-by, in readiness to provide cover for the West Midlands.
It is believed the employers have asked for 65 vehicles, each to be crewed by two people, as part of their contingency plans - with each volunteer expected to be paid up to £150 a day for time and costs incurred.
This would put the cost of strike cover at £19,500 a day.
An overtime ban could take just hours to bite, as some parts of the region are already facing a staff shortage, and calls answered by volunteer crews could face longer response times.
If the dispute is not resolved by February 11, a string of sporting fixtures could be affected if ambulance crews do not attend - as part of safety regulations - including Villa v Newcastle, Wolves v Crewe and Walsall v Scunthorpe.