Cumbria and southern Scotland are among the worst areas in the UK for roadside phone coverage.
Figures from the RAC Foundation show large stretches of road are without coverage.
The research found:
Travellers in the region that rely on their phones, may find themselves in a difficult situation if they break-down or lose their sense of direction in areas that have no signal.
Steve Gooding, the RAC Foundation's Director, said more needs to be done to improve signal to make roads safer and reduce congestion.