GSM
Definition:
GSM stands for Global System for Mobile communications and represents a standard for mobile phone communication. Consumers with GSM mobile phones can often roam between different cellular providers or switch cellular services without having to purchase a new mobile phone.
Here's a word you may not know...
UPS
An Uninterruptible Power Supply, or UPS, is a device that can supply battery power to any electrical devices plugged into it. You will typically find a UPS connected to a computer or server to keep it running during a power outage. Battery time varies for each UPS and is usually proportional to the price tag. A smaller, home-based UPS usually provides enough battery power to sound an alarm and give a person enough time to save open files and safely shut down his or her computer. Conversely, an enterprise UPS will provide enough battery power for an entire room full of servers to run for an extended period of time.