Originally you had Analog Cell Phones - the old brick and flip phones. Then came Digital Cell phones - Digital allows for 10+ times the data to be carried over the same amount of bandwidth that one Analog signal would use. Then came GSM!
http://www.phonescoop.com/glossary/term.php?gid=3
Global System for Mobile Communication.
GSM is currently the dominant 2G digital mobile phone standard for most of the world. It determines the way in which mobile phones communicate with the land-based network of towers.
GSM has not been the most popular standard in the United States in the past. CDMA and TDMA, competing standards, together shared most of the market.
However, AT&T Wireless and Cingular, who both used TDMA technology, recently switched to GSM technology. This will narrow the major technologies in the US to two - GSM and CDMA.
The most visible feature of GSM are SIM cards. SIM cards are removable, thumbnail-sized smart cards which identify the user on the network, and can also store information such as phone book entries. SIM cards allows users to switch phones by simply moving their SIM card from one phone to the other.
oh sure.. ask the guy that works at a phone company...
http://www.phonescoop.com/glossary/term.php?gid=3
Global System for Mobile Communication.
GSM is currently the dominant 2G digital mobile phone standard for most of the world. It determines the way in which mobile phones communicate with the land-based network of towers.
GSM has not been the most popular standard in the United States in the past. CDMA and TDMA, competing standards, together shared most of the market.
However, AT&T Wireless and Cingular, who both used TDMA technology, recently switched to GSM technology. This will narrow the major technologies in the US to two - GSM and CDMA.
The most visible feature of GSM are SIM cards. SIM cards are removable, thumbnail-sized smart cards which identify the user on the network, and can also store information such as phone book entries. SIM cards allows users to switch phones by simply moving their SIM card from one phone to the other.