More than 70% of firms face ‘not spots’ of patchy or no mobile internet coverage in their local area, a British Chambers of Commerce (BCC) survey says.
It found the problem was particularly bad in the countryside, where 90% of firms struggled, although 56% in cities also complained.
The BCC, which surveyed more than 1,400 mainly small businesses, said the issue was “hobbling” productivity.
The UK’s digital infrastructure lagged behind other countries’, it added.
According to the research, almost a third of all businesses said their mobile internet connection was generally unreliable, with the proportion rising to 54% in rural areas.
It also found many were not accessing the highest connection speeds, with just 42% reporting being able to access a 4G connection.
Dr Adam Marshall, director general of the BCC, said: “Time and again, I hear from frustrated businesspeople who can’t use their mobiles or access the internet when they need to.
“These are basic requirements for companies to work on the move, trade online, and connect with customers and suppliers.”
He said that while rural businesses were particularly affected, “not-spots” were prevalent across the UK, including in parts of the City of London.
The BCC called for planning restrictions to be relaxed, to allow for more taller mobile phone masts to be built to improve coverage.
It also said regulator Ofcom needed to do more to hold providers to the promises they made about coverage in advertising.