This map is only a guide and not a guarantee of service availability in a particular location. It shows outdoor coverage only and may include locations where mobile devices don't work. As with all radio-based systems, service may be affected by a number of local factors, such as building materials, tree cover and weather conditions. You'll need a 4G phone, SIM and plan as well as 4G coverage to use 4G. Why the map isn't perfect. *Where we plan to switch on 4G in an area within the next 3 months. Unfortunately we can't guarantee if your postcode will be covered. You can sign up to receive email alerts.