What is a multi-network IoT SIM?
A multi-network IoT SIM (also called a multi-IMSI or steered multi-network SIM) is provisioned to work across multiple UK mobile networks from a single SIM. Unlike basic roaming SIMs, multi-network SIMs use more sophisticated profile management to select and stay on the best available network at any location. They are widely used for UK IoT deployments requiring coverage continuity across different geographic areas.
Steered vs non-steered multi-network SIMs
A steered multi-network SIM is configured to prefer specific operators in a defined priority order. The SIM will attempt the preferred operator first and only roam if that operator is unavailable. A non-steered SIM selects any available network based purely on signal, with no operator preference. For IoT deployments, steered SIMs give more predictable behaviour and allow network selection to be aligned with the operator that has been tested and validated for each site using CellTester.
UK PLMN codes for IoT SIM configuration
| Operator | PLMN | Notes |
|---|---|---|
| EE | 234-30 | Primary network for UK IoT — widest 4G coverage |
| Vodafone UK | 234-15 | Strong rural coverage; 5G SA leader |
| Three UK | 234-20 | Good urban coverage; unlimited data options |
| O2 UK | 234-10 | Satellite LTE partnership with SpaceX |