Before diving into the specifics of Qualcomm's tools, it's essential to understand what SIM locks and network locking entail. A SIM lock, also known as a network lock or carrier lock, restricts a mobile device to work only with a specific SIM card from a particular network provider. This means if a device is locked to a specific network (e.g., Verizon, AT&T, T-Mobile), it will not accept a SIM card from another network (e.g., Vodafone, Orange).