Our online glossary is here to help you make sense of the terminology used in the cell phone industry.

Definition of "HSDPA"
HSDPA stands for high-speed downlink packet access. It is an upgraded form of UMTS in that it allows for faster download speeds. Current implementations of HSDPA can achieve speeds as fast as 3.6Mbps, but future versions are expected to reach 14Mbps. Not to be confused with HSUPA, which is a UMTS upgrade that provides a greatly increased uplink connection for faster uploads.
Also known as: "High-Speed Downlink Packet Access"

Definition of "HSUPA"
HSUPA stands for high-speed uplink packet access, and is an upgrade to UMTS that allows for uplink connections as fast as 5.76Mbps. HSUPA is similar to EV-DO Rev A in that it can be added to existing networks to increase upload speeds from compatible devices.
Also known as: "High-Speed Uplink Packet Access"

Definition of "UMTS"
UMTS is a 3G networking standard used throughout most of the world as an upgrade to existing GSM mobile networks. UMTS makes use of WCDMA, a technology that shares much with CDMA networks used throughout the world, though it is not compatible with them. Base level UMTS networks are generally capable of downlink speeds as fast as 384kbps. Newer HSDPA variants are capable of rates as high as 3.6Mbps or more. Originally used only on the 2100MHz frequency band in Europe, UMTS is now supported on the 850MHz and 1900MHz bands in North America.

Definition of "2G"
2G is short for Second Generation, the name usually given to original GSM, CDMA, and TDMA networks.

Definition of "3G"
3G, or Third Generation, is a somewhat generic term for network technologies that the ITU classifies as part of their IMT-2000 specification. Generally, wireless network technologies must be able to provide a mobile device with a downlink connection speed of 384kbps in order to be considered a 3G technology. The most used 3G technologies are WCDMA, CDMA 1xEV-DO, and, technically, EDGE and CDMA 1xRTT.
Also known as: "third generation" 

Definition of "4G"
4G is the term used to refer to the next wave of as yet unknown mobile technologies that will be used to replace current 3G networks. It is expected that WiMAX will be one of the favored 4G technologies.
Also known as: "fourth generation"

Definition of "GSM"
GSM is a TDMA based wireless network technology developed in Europe that is used throughout most of the world. GSM phones make use of a SIM card to identify the user's account. The use of the SIM card allows GSM network users to quickly move their phone number from one GSM phone to another by simply moving the SIM card. Currently GSM networks operate on the the 850MHz, 900MHz, 1800MHz, and 1900MHz frequency bands. Devices that support all four bands are called quad-band, with those that support 3 or 2 bands called tri-band and dual-band, respectively.
Also known as: "Global System for Mobile Communications", "Groupe Special Mobile"

Definition of "SIM card"
A SIM card is a small card that contains a mobile network subscriber's account information. This allows the phone using the card to attach to a mobile network. About half the size of a typical stamp, the SIM card is most commonly associated with GSM and UMTS handsets. Moving a SIM card from one phone to another allows a subscriber to switch mobile phones without having to contact their mobile network carrier. SIM cards can also be used by a phone to store limited amounts of data, such as phone numbers and text messages. CDMA based phones typically do not have SIM cards and instead rely on an ESN or MEID.
Also known as: "SIM", "Subscriber Identity Module"

Network Coverage in JAPAN

Making calls, sending text messages and using GPRS/EDGE mobile data connection in JAPAN is not available using the existing 2G frequency bands.

2G capabilities:

Making calls, sending text messages and using mobile data connections in JAPAN is available via the existing 3G network. Use a mobile phone that supports at least the frequency band filled as “Required” below.

3G capabilities: