Is there a factory unlock for iPhone 4S baseband 2.0.12 (iOS 5.1.1)?

Yes, factory unlocking is available for the iPhone 4S regardless of its baseband or firmware version, including iOS 5.1.1 with baseband 2.0.12. Unlike software unlocks which depend on specific vulnerabilities, a factory unlock, also known as an IMEI unlock, is processed through Apple's GSX database. Once your IMEI is whitelisted by the carrier or a third-party service, you simply need to connect the device to iTunes or a Wi-Fi network to complete the activation process. For those who cannot get a carrier unlock, hardware interposers like the Gevey Ultra S or R-SIM were historical alternatives, but a permanent IMEI factory unlock remains the best solution.