Britain is 54th in the world for 4G coverage, and the typical user can only access 4G barely half the time, according to the National Infrastructure Commission.
"Our roads and railways can feel like digital deserts and even our city centres are plagued by not spots where connectivity is impossible," it says.
"That isn't just frustrating, it is increasingly holding British business back as more and more of our economy requires a connected workforce."
See also: Call to improve rural mobile coverage
Figures show that coverage makes it possible to make and receive phone calls across only 52% of UK landmass and that the discrimination felt by rural areas is acute.
The evidence also suggests how mobile areas are focusing their investments on rolling out infrastructure in rural areas.
Roll out of 4G services mean that coverage is available in 89% of locations within urban areas, more than double the coverage figures for rural areas (37%).
Rural business leaders are calling for urgent talks to address what they described as the "continued neglect" of rural areas by mobile network operators.
CLA policy director Christopher Price said: "It is shocking that Ofcom has no confidence that the operators have a plan to deliver the coverage rural areas need.
"This comes despite legally binding commitments made by the mobile companies that coverage would be delivered by the end of next year. Today's report casts this prospect in to serious doubt.
"We are seeking urgent meetings to discuss what can be done to force the industry to deliver more than just promises but actually roll out the infrastructure required to connect our countryside.
Mr Price said ministers should impose stringent conditions which require the operators to deliver the extended coverage they had failed to do to date.
The UK government is expected to commence the tender process for acquisition of licence rights for new spectrum capacity next year.
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