The compatibility of a SIM card between iOS and Android devices is largely dependent on the SIM card’s physical size and whether the devices are unlocked. Modern iPhones and Android phones primarily utilize nano-SIM cards. If both devices use the same size SIM, it can physically fit. However, cellular network lock status will dictate if it will function correctly.
The ability to transfer a SIM card between different operating systems offers flexibility for users switching between devices. Historically, variations in SIM card sizes posed a barrier, necessitating replacement cards. The advent of standardized nano-SIMs has simplified this process. However, network locking, a practice often employed by carriers to restrict device usage to their network, can prevent successful SIM card transfer even if the card physically fits and is activated.