rSIM adapters are sold under several brand names, including GPP, X-SIM and Heicard. The adapter works around the lock rather than removing it: the phone stays carrier-locked, and it depends on the adapter staying in place to keep working on a different network.
rSIM-dependent phones are most common in grey-market secondary trading, particularly US carrier-locked iPhones routed into LATAM and African markets. The term "software unlock" is sometimes used for a similar jailbreak-based workaround, which carries comparable risks.
Why rSIM-dependent phones are unreliable
- Detectable. The phone often still shows as SIM-locked in Settings > General > About even when a different carrier's SIM is working.
- Fragile across updates. iOS updates can break rSIM workarounds, and in some cases leave the device unusable until it is returned to a working state.
- Inconsistent service. Calls and data can work intermittently, LTE band support may be reduced, and FaceTime or iMessage activation can fail.
Why wholesale buyers price rSIM-dependent units lower
Lots described as "works on any carrier with rSIM" or "GPP unlocked" should be priced as carrier-locked, not as factory-unlocked. The adapter is a convenience, not a genuine unlock, and downstream buyers price in the support issues, returns risk and update fragility that come with it. Confirm the lock status per IMEI before agreeing a price, and ask the seller to state plainly whether the units need an adapter.
rSIM vs eSIM
An eSIM is an embedded SIM: a chip built into the phone that stores carrier profiles downloaded over the air. It is a standard feature, not an adapter, and it does not bypass a carrier lock, so a locked phone's eSIM is still restricted to that carrier. An rSIM is a physical add-on layered over a removable SIM to work around the lock. The two are unrelated technologies that happen to share a similar name.
Not to be confused with a separate product also branded rSIM, the "resilient SIM" from Deutsche Telekom IoT and Tele2 IoT, which switches between operator profiles for connected IoT devices. It has nothing to do with iPhone adapters.