The ability to make voice calls and send text messages over a wireless internet connection on a mobile device using the Android operating system, even in the absence of a physical subscriber identity module (SIM) card, presents a distinct technological capability. This feature allows communication independent of traditional cellular network connectivity. For instance, an Android tablet without a SIM card, or a phone with a deactivated SIM, can still place calls if connected to a Wi-Fi network.
This functionality offers several key advantages. It can provide a communication lifeline in areas with poor or non-existent cellular coverage but reliable Wi-Fi. It also enables the use of devices that were previously reliant on cellular subscriptions for communication. Historically, mobile devices were strictly tied to cellular networks, requiring a valid SIM for almost all communication. The advent of Voice over IP (VoIP) and its integration into operating systems such as Android has decoupled communication from this strict dependence.