A normal SIM holds one identity, one IMSI, tied to one operator. The moment that operator is weak or unavailable, the device is stuck. A multi-IMSI subscriber holds several identities and can switch between them over the air, so it behaves like holding several operator subscriptions on one piece of hardware.
How steering decides
- Signal quality and the radio technology each candidate network offers.
- Cost, so the subscriber prefers the most economical network that still meets quality.
- Policy you set, for example pinning a region to a preferred partner or avoiding a carrier entirely.
What this buys you
Resilience and reach without touching the device. If a network degrades, the subscriber falls back to the next best IMSI automatically. When you enter a new country, the right local identity is already available, so there is no permanent-roaming risk and no SIM swap.
Tip
Steering is invisible to your application. You always talk to one subscriber; Simsonic moves the identity underneath it.