GSM - Terminology and Evolution

What is GSM?

GSM stands for Global System for Mobile Communication.

GSM is a digital cellular system that started in Europe in the early 1980s.

GSM uses a combination of TDMA (Time Dvision Multiple Access) and FDMA (Frequency Division Multiple Access). This insures that all channels are digital and allows for more channels of communication.


GSM is readily available in the following areas across the world:

• North America - Primarily 1900 MHz also 850 MHZ and 1800MHz

• India, Asia-Pacific, Middle East, Africa, South America - Primarily 900MHz, 1800 MHz and 1900 MHz

The higher frequency bands allow for greater capacity and higher subscription densities thus being very cost effective.

Since GSM is available worldwide, it makes it easier to allow roaming if a roaming agreement exists between your service provider and the country you are visiting.

One of the advantage of GSM over CDMA (Code Division Multiple Access - http://en.wikipedia.org/wiki/CDMA) is that you need a SIM card (Subscriber identity Module). This card, also referred to as a Smart Card, gives a subscriber flexibility to change cellular phones without having to activate the phone. The SIM card is made up of non- volatile memory chip and it contains the following minimal information:

• The subscriber's identity number
• The subscriber's telephone number
• The original network that the subscriber is registered to

The information is read from the SIM card and transmitted to the network to identify the subscriber.
If a person travels to multiple countries, then, the person can purchase just the SIM card of the local service provider and use the same handset. Therefore potentially avoiding international roaming.

GSM Terminology and Description:

Operator Name	Carrier Name
PMN	Public Mobile Network. 5 character code to identify the network. The first 3 characters identify the country, the next two the carrier within that country
VPMN	Visited Public Mobile Network operator
HPMN	Home Public Mobile Network operator. The operator the subscriber belongs to. Used to bill while in roaming mode.
BID	Billing Identifier. Only used in North America to identify the market. Billing between operators is done at the PMN level.
IMSI	International Mobile Subscriber Identity. The subscriber’s account number
MSISDN	Mobile Subscriber telephone number. The number you dial to call the subscriber. Also known as Mobile ID number
SIM	Subscriber Identity Module. The smart card that contains subscriber information, including IMSI, available services, speed dial lists, groups distribution lists, etc
Roaming	When a subscriber is out of the zone coverage of their HPMN. The subscriber is roaming. This can be both national or international depending on the roaming agreements that were signed between the HPMN and the VPMN
TAP	Transferred Account Procedure. Standard roaming billing format
CDR	Call Detail Record
RAP	Returned Account Procedures. Automated process for returning rejects and or warnings. Usually a clearing house is used between the HPMN and the VPMN. In North America Syniverse is one of the clearing houses used for this purpose and other functions such as portability
Portability	The port or transfer of a telephone number from one PMN to another. It refers to both port-in and port-out

GSM Technology Evolution and Data Rate Speed:

1G - Analog
2G - 5.6 kbps - 13 kbps
3G - 1.2 mbps
4G (LTE) - 172 mbps - 326 mbps (download); 86 mbps (upload)



For more information, visit: http://www.gsmworld.com/