3G 'not-spot' data: network switch-off update

07 September 2023

Mobile network operators have started, or are preparing to start, switching off their 3G networks. As they do, we estimate that – as well as existing 'not spots' – a small number of properties might lose access to a reliable, indoor, 3G-only mobile service.

We have published a list of postcodes (below) which may be affected once Vodafone, EE and Three switch off their networks in 2024, as 3G-only devices in those areas could lose their ability to connect to a 3G mobile network. In 2025, VM02 will also be turning off its 3G network.

This data is to help providers of services (especially telecare) identify any customers that could lose 3G connectivity. For telecare, this loss of 3G coverage might affect around 1-2% of a small number of devices that rely on 3G-only roaming SIMs, supplied by a provider outside the UK. The data does not apply to 3G devices that can also connect through 2G or 4G networks.

To help preparations for these switch-offs, we have also published some advice for Internet of Things and third-party device suppliers to support work being carried out by mobile operators and set out in our 3G and 2G switch-off: Our expectations of mobile providers document.

  • The published list of postcodes is based on mobile network operators' predictions of their 3G outdoor coverage, to which we have applied a range of additional assumptions on signal losses to help predict the likely 3G signal strength indoors.
  • Indoor mobile signals vary hugely in any given premises and between different premises, and reliably predicting indoor coverage is not trivial. Given the particular risks associated with telecare, we have taken a more conservative approach to the coverage data than that published in Connected Nations (PDF, 287.1 KB).
  • Some postcodes listed in the data do not contain ‘premises’, as defined by Ofcom in Connected Nations but are included for completeness.
  • This list is not definitive for the purposes of identifying properties that will become additional 3G not-spots once Vodafone, EE and Three switch off their 3G networks. Instead, this data should be used with other potential indicators of reliable 3G mobile signal loss, to identify customers who could be affected and require support to ensure continuity of service.

  • This data should only be used to identify existing users of 3G-only devices; it is not suitable for future planning or other purposes.
  • The data is particularly useful to 3G-only network roaming SIMs that have been supplied by a mobile network operator (MNO) outside the UK. It complements the existing work UK MNOs are doing to identify third-party users of their 2G and 3G networks.
  • All 3G-only SIMs will need to be replaced before VM02 switches off its 3G network in 2025.

3G not-spot data (XLSX, 2.9 MB) -  current data

Published: 19 October 2023

3G not-spot data (CSV, 3.1 MB) - This previously published data has been superseded by the above file and has been retained for reference purposes only.

Published: 28 July 2023

Other 'not-spot' data

Alongside our Connected Nations: Summer 2023 update, we published a list of postcodes at which we estimate that some properties cannot get a reliable indoor mobile signal from any mobile network operator. This is to help communications providers identify any customers who depend on their landline, as they migrate customers to new digital voice services.

Not-spots by postcode (ZIP, 52.5 KB)
Published 7 September 2023

We remind providers of the guidance (PDF, 1003.8 KB) we published in 2018: this set outs the steps we expect a provider to take to establish whether or not a customer depends on their landline. This not-spot data might help with one of those steps.

Technical notes

  • This data is based on mobile coverage information from April 2023.
  • The list consists of postcodes where we have judged that at least one property within the postcode will not be able to receive a reliable voice service from any mobile network.
  • Given the assumptions necessary to estimate indoor coverage, and the mapping of mobile geographic coverage data to UK postcode areas, there might be properties in other postcodes that cannot receive a reliable voice service.
  • On the other hand, there might be properties in the postcodes we have listed that can receive a reliable voice service.
  • So, do not assume the list to be definitive for the purposes of identifying landline-dependent properties.

We will update the list periodically and at least once a year.