The global system for mobile communications (English Global System for Mobile communications, GSM, and originally from the French groupe spécial mobile) is a standard system, royalty-free, digital mobile phone. A GSM client can connect through your phone to your computer and send and receive emails, faxes, surf the Internet, access to the computer network security acompany (LAN/Intranet) and use other functions of digital data, including short message service (SMS) or text messages. What are the differences between GSM and UMTS? The GSM system operates by TDMA, ie, time is divided into slots and each user is assigned a slot, ie, a period for which data can be transmitted. Therefore each channel is shared by a ndetermined number of users. The system is a UMTS (WCDMA) code division multiple access broadband. In this system there are no time slots and GPRS. All users transmit simultaneously on the channel, but each user signals are encoded with a unique code so that even though we think that an "indecipherable signal" is formed by using the same frequencies simultaneously, It is not toyes, because the base station is capable of decoding and re perfectly separate each of the communications received from different users. This obviously implies a much higher channel utilization, to not share in time.

One hertz is one cycle per second, meaning repeating cycle as an event. For example, hertz is applied physics measuring the number of times for a second wave (either acoustic or electromagnetic) is repeated or can be applied, among other uses, to ocean waves that reach the Beach vibrations per second or a solid. The quantity that measures the frequency hertz is called,in this regard, the inverse of the period. One hertz is an oscillation frequency of suffering a particle over a period of one second.