Everything you need to know about switching mobile in the UK

Text PAC to 65075 from your current SIM. Your old provider must reply within 60 seconds with a Porting Authorisation Code valid for 30 days. Give the PAC to your new network when you sign up and they handle the transfer within one working day. The process is free and governed by Ofcom General Condition C7. Full walkthrough in our switch UK mobile provider guide.

Yes. You can request a PAC at any point, even mid-contract. However, if you port away before your contract end date, you may owe an early termination charge calculated on the remaining monthly payments (minus a discount for saved costs). Check your contract terms first. If you are within the last 30 days of contract, you usually owe nothing. The PAC process itself is always free regardless of your contract status.

Just text PAC to 65075 again from your current SIM. Your network must issue a new PAC free of charge every time you request one. There is no limit on how many times you can request a PAC. Each new code is valid for 30 days. The previous code becomes invalid once a new one is issued, so give the most recent code to your new network.

giffgaff runs on the O2 network. To switch to giffgaff: order a free SIM at giffgaff.com, activate it, then text PAC to 65075 on your old SIM and give the code to giffgaff during activation. To switch away from giffgaff: text PAC to 65075 on your giffgaff SIM. giffgaff must reply within 60 seconds. Hand the code to your new network and your number transfers within one working day. Your giffgaff account closes automatically.

Once your number ports to the new network, the old SIM stops working. You cannot receive calls or texts on it. Any credit, data allowance or unused minutes on the old SIM are forfeited unless your old provider has a specific refund policy. Make sure you have backed up any contacts stored on the SIM itself before porting. Most modern phones store contacts in the cloud (iCloud, Google), so this is rarely an issue.

Use the free Ofcom Mobile Coverage Checker at checker.ofcom.org.uk. Enter your postcode to see indoor and outdoor 4G and 5G predicted coverage from EE, O2, Vodafone and Three on a single map. Note that the checker shows predicted coverage based on network models, not real-world measurements. For a more accurate reading, check the individual network coverage maps and look at independent reviews from users in your area. Full steps in our check UK network coverage guide.

The biggest wins come from a few settings changes: enable Low Data Mode (iOS) or Data Saver (Android) to stop background app refresh; set music and podcast apps (Spotify, Apple Music) to download over Wi-Fi only; disable auto-play video in social apps; and turn off photo backup over mobile data. Together these typically cut usage by 30 to 50% without changing how you actually use your phone. Detailed steps for both platforms in our tips to lower mobile data use guide.

This error means the SIM card is not activated or the network has not yet registered it. The four checks to run in order: (1) restart the phone after inserting the new SIM; (2) check the APN settings match the network (go to Settings and search APN); (3) perform a network reset (Settings and General Management and Reset and Reset network settings on Android); (4) reseat the SIM in the tray to ensure clean contact. If none of these work, the SIM itself may be faulty and needs replacing. Full diagnostic steps in our SIM not provisioned fix guide.