Mobile phone coverage in Scotland is poorer than other parts of the UK, says Ofcom.
A report from Ofcom suggests that only 38% of the landmass has good 4G coverage from all operators - while 82% of England is covered.
The Federation of Small Businesses (FSB) called for stronger action to improve Scottish mobile coverage.
According to Ofcom, 38% of Scotland's landmass has good 4G coverage from all operators compared with the UK average of 66%; 4G mobile coverage from at least one operator is available in 78% of the landmass and just over half of Scotland can receive voice services from all four operators, up from 39% in June 2017.
Ofcom said it would attach binding coverage rules for mobile operators when it auctions off two new frequency spectrums.
Philip Marnick, Ofcom's spectrum group director, said: "Mobile coverage has improved across the UK this year, but too many people and businesses are still struggling for a signal. We're particularly concerned about mobile reception in rural areas.
"As we release new airwaves for mobile, we're planning rules that would extend good mobile coverage to where it's needed. That will help ensure that rural communities have the kind of mobile coverage that people expect in towns and cities, reducing the digital divide."
The FSB said it was wrong that customers in Scotland faced an inferior mobile service, despite paying the same charges as elsewhere in the UK.
Andrew McRae, the FSB's Scotland policy chairman, said: "While it is good to see Ofcom note that this is unsatisfactory, we need to see action from them, the UK government and mobile operators to address this long-standing problem."