A new web tool will let mobile phone users check the signal coverage of the four main networks across the UK.
The service released by regulator Ofcom lets people enter a postcode or zoom in and out of a map to compare the 3G, 4G and voice call signal coverage of EE, Vodafone, O2 and Three down to 100m anywhere in the country.
The map is colour-coded for signal strength and also shows coverage inside and outside of buildings as well as topographical information to help to identify natural obstructions to coverage such as valleys and hills.
"Ofcom's Mobile Coverage Checker provides a single stop for consumers and businesses across the UK to discover the quality of the mobile coverage in areas where they live and work, or somewhere they intend to move," said the regulator.
"Consumers increasingly expect a reliable mobile service. The new map therefore shows where reliable coverage is likely to be available, whatever type of handset is used, using new research by Ofcom into the signal strength needed to provide a good consumer experience.
"The new map is designed to support consumers in choosing a service that best suits their needs, while promoting competition between mobile operators."
Ofcom says the service has taken account of the increasing shift from external aerials on mobiles to the internal aerials found on modern smartphones, which can sometimes be less effective at picking a signal.
The regulator is also encouraging users to report their own experiences to help continually improve the map's accuracy.
Ofcom's chief technology officer Steve Unger said: "Access to reliable mobile phone coverage used to be a 'nice to have'. Now it's essential to many people's lives.
“We believe our map is the most comprehensive tool available to consumers and businesses to check mobile coverage. We’re encouraging people to feed back after using the map, so we can continue to improve its accuracy.”