R-SIM (and similar branded variants: GPP, X-SIM, Heicard) are SIM adapters that intercept the carrier-lock handshake on iPhones and allow a locked device to register on a different carrier's network. Software unlock refers to the equivalent jailbreak-based workaround. Both are widely used in grey-market secondary trading, particularly for US carrier-locked iPhones routed into LATAM and African markets.
For wholesale buyers, R-SIM and software unlocks introduce three risks. First, the workaround is detectable: an iPhone running an R-SIM frequently shows in Settings > General > About as “Carrier Lock: SIM-Locked” even when using a different carrier's SIM. Second, iOS updates regularly break R-SIM workarounds, sometimes bricking the device. Third, calls and data may work intermittently, with reduced LTE band support and FaceTime/iMessage activation failures.
Wholesale practice: lots described as “works on any carrier with R-SIM” or “GPP unlocked” should be priced as carrier-locked, not as factory-unlocked. The R-SIM workaround is convenience, not a legitimate unlock, and downstream buyers price-protect against the operational issues that come with it.