An eSIM is a SIM built into the phone rather than a card you insert. Most networks will now issue your regular UK plan as one, delivered by QR code or through their app, with no waiting for the post. It is the same plan and the same number; only the delivery differs.
Why people like it
- Instant. Sign up in the evening, be connected in minutes.
- Two lines on one phone. Most phones support one eSIM alongside a physical SIM, or two eSIMs. A work number and a personal number, or your UK plan plus a travel eSIM abroad.
- Nothing to lose or break. No tray, no tiny card.
Where it bites
- Changing phones. A physical SIM moves in ten seconds. An eSIM has to be transferred, which on some networks means a new QR code from them — occasionally with a delay or a small fee. Newer phones can transfer eSIMs directly, but not all networks support that.
- A broken phone. If the phone dies you cannot pop the SIM into a spare while you sort it out; you need the network to reissue the eSIM.
- Older or cheaper handsets. Not every phone supports eSIM, and some support only one at a time.
Switching networks with an eSIM
Exactly the same as with a card: text PAC to 65075 for the code, and give it to the new network. The new network then issues its eSIM. Keep the old one active until the number has moved.
Our take
For a phone you will keep for a while, eSIM is the more convenient option and there is no reason to avoid it. If you swap phones often or keep a backup handset, a physical SIM is less hassle. Networks that offer both usually let you switch between them free, so it is not a permanent decision. See which plans are available on the SIM-only page; most now offer eSIM delivery at checkout.