Where has the best and worst mobile signal?
We already know that London's kitchens are officially dead zones, but when you're heading on holiday, moving house or considering switching network, it's pretty difficult to tell.
Now Ofcom has put together possibly the most comprehensive map of the state of the UK's mobile network coverage, including voice calls, 3G and 4G.
It's based on all the major mobile networks, EE, O2, Vodafone and Three, as well as networks such as Virgin Mobile, TalkTalk and Tesco Mobile, each of which uses one of the big four networks.
You can select whether you're indoors or outdoors (the material the building is made of can actually make a difference to signal) and search any location across the nation right down to postcode.
So, no longer will you have to resort to this sort of thing.
"Access to reliable mobile phone coverage used to be a ‘nice to have’. Now it’s essential to many people’s lives," said Ofcom's tech chief Steve Unger.
“We believe our map is the most comprehensive tool available to consumers and businesses to check mobile coverage. We’re encouraging people to feedback after using the map, so we can continue to improve its accuracy.”