O2 were formed when BT sold their Cellnet mobile network a couple of decades back. It’s been around for a long time and is well recognised as a UK brand. Owned by Telefonica, it was nearly bought by Three‘s parent company in 2016 but the sale was blocked by the EU.
Given O2’s history in the UK, it has excellent coverage of 2G, 3G and now 4G across the UK, although it’s allocation of 4G frequency is somewhat smaller than rival networks. You can see more about the 4G frequencies available in the UK here.
O2 sells prepaid and monthly mobile plans to home and business users. They no longer sell home broadband, but they do have a dedicated mobile broadband section.
Buyers often like O2 given the history and stability of their network.
Where to buy
O2 sell directly from their website. You can find O2 mobile phones here and O2 mobile broadband here. The Carphone Warehouse are approved resellers of O2 plans, so you can often take advantage of their handset offers to find a good deal.
Sometimes, but less reliably so, you can also find prepaid O2 SIM cards on Amazon such as this.
O2 in the News