________ is a personal security code for GSM subscribers
Voicemails is a personal security code for GSM (global system for mobile communication) subscribers.
GSM (global system for mobile communication) services are a standard collection of applications and features available to mobile phone subscribers all over the world. The GSM standards are defined by the 3GPP collaboration and implemented in hardware and software by equipment manufacturers and mobile phone operators.
GSM provides recommendations, not requirements. The GSM specifications define the functions and interface requirements in detail but do not address the hardware.
A voicemail system is a computer-based system that allows users and subscribers to exchange personal voice messages; to select and deliver voice information; and to process transactions relating to individuals, organizations, products and services, using an ordinary telephone. The term is also used more broadly to denote any system of conveying a stored telecommunications voice messages, including using an answering machine.