A £55m investment in a new radio system for the Welsh Ambulance Service is due to be announced by the Welsh Assembly Government.
New radio systems will be installed in all 827 vehicles
Currently, a third of Wales is out of radio coverage, with different control rooms using different systems.
The 10-year deal funded by the assembly government means ambulances will have the same system as other 999 services.
Ahead of May's assembly elections, Wales' other main parties pledged their commitment to improving the service.
The Welsh Ambulance Service has suffered a turbulent 12 months.
In May 2006, the acting chief executive, Roger Thayne, walked out after two months in the post saying the trust was in "crisis" and later claiming 500 people were dying each year because of failings.
His successor as interim chief executive, Anton van Dellen, also resigned after two months in the job, saying he was unable to commit long-term to the post.
In August, Alan Murray was appointed chief executive and said improvements would be made by Christmas.
But official figures released last November showed emergency response times were the worst since 2003.
The assembly government said the investment in the new radio system was part of plans to modernise the service and was in addition to £16m funding announced in October for new vehicles.
Ambulance control rooms will be upgraded and new radio systems installed in all 827 vehicles, including 454 ambulances and three air ambulances.
Welsh Health Minister Brian Gibbons said the investment would help "transform and modernise" the service and would also provide a safer working environment for staff.
Dr Gibbons said: "The new communications system will provide far greater radio coverage across Wales, compared with about 65% at the moment.
"This will help the control rooms keep in touch with the crew and will enable the trust to become more efficient and effective in deploying their resources."
Mr Gibbons added the new system would ultimately improve response times and patient care.
Welsh Ambulance Service NHS Trust Chief Executive Alan Murray said the investment would mean the service had the latest digital communications technology.
"It will replace all existing communication equipment in ambulance control centres and stations and will provide staff with immediate and dependable communications with other emergency services," he said.
"The investment marks a significant step forward in the trust's modernisation of the service in Wales and will enhance patient care and improve service delivery."