Access Point Name is a URL that is used within the GPRS network to route to the correct GGSN and to identify the services that should be provided to the user of the APN. For example, users of one APN might use a VPN connection, while users of another would not.

are used by a mobile application to control a wireless modem. The AT command set consists of a series of short text strings which combine together to produce complete commands for operations such as dialing, hanging up, and changing the parameters of the connection. The command set for GSM modems is specified in 3GPP specifications, TS 27.007 and TS 27.005 (for SMS-related commands). The standardized commands include some commands that are optional. Therefore, most wireless modem makers support most, but not all standardized commands. In addition, most modem makers include additional vendor-specific AT commands.

Gateway GPRS Support Node is a network node that acts as a gateway between a GPRS wireless data network and other networks such as the Internet or private networks. When a GPRS device establishes a PDP Context to a specific APN, the APN selected determines the GGSN to be used.

is a packet oriented mobile data service available to users of GSM. It provides theoretical data rates of up to 170kbps. Data rates of up to 40kbps are experienced in real-world networks, depending upon device capabilities, network configurations and network load.

GSM is a cellular network, which means that radio spectrum is separated into individual coverage areas - cells, each served by a base station. Mobile devices connect to the network using the radio channels available in the local serving cell.

The Home Location Register is a central database that contains details of each mobile user, including information on the subscriber identities (IMSI, phone number) and the services to which the user has subscribed (e.g. APNs, fixed IP address, roaming restrictions)

Integrated Circuit Card ID. This is the identifier of the actual SIM card itself - i.e. an identifier for the SIM chip. It is possible to change the information contained on a SIM (including the IMSI), but the identify of the SIM itself remains the same.

International Mobile Subscriber Identity. This is a unique identifier that defines a subscriber in the wireless world, including the country and mobile network to which the subscriber belongs. It has the format MCC-MNC-MSIN. MCC = Mobile Country Code (e.g. 310 for USA); MNC = Mobile Network Code (e.g. 410 for AT&T), MSIN = sequential serial number. All signaling and messaging in GSM and UMTS networks uses the IMSI as the primary identifier of a subscriber. The IMSI is one of the pieces of information stored on a SIM card.

Any device that embeds a modem.

A GSM/GPRS/EDGE wireless radio

The Mobile Switching Center is the primary service delivery node for GSM, responsible for handling voice calls and SMS as well as other services. Most GPRS devices also have the capability of using services provided by the MSC (e.g. voice, SMS, USSD). For this reason, a GPRS device will normally first register on an MSC, known as GSM registration, before attaching to the local SGSN.

Mobile Station ISDN number. This is the full phone number of a subscriber, including the national country code (e.g. 1 for US, 44 for UK, etc.). The purpose of the MSISDN is simply to allow a device to be called. A subscriber can have multiple MSISDNs (e.g. one phone number for business, one for personal calls, one for fax, etc.), but generally only one IMSI. The MSISDN does not need to be stored on the SIM card. In cases where it is stored on the SIM, the main reason is so that the user can use check to see what their own MSISDN is (in case they forget). The MSISDN is never signaled to of from the device

is a GPRS data session. Through the establishment of a PDP Context, the device is assigned an IP address, which is a prerequisite for sending or receiving IP traffic. The establishment of a PDP Context creates a data path from the mobile device to the local SGSN to the serving GGSN, which controls the required Access Point Name (APN). In order to establish a PDP Context, the mobile device must first register with the serving SGSN. This process is known as GPRS Attach.

A Serving GPRS Support Node is responsible for the delivery of data packets from and to the mobile stations within its geographical service area. Its tasks include packet routing and transfer, mobility management (attach/detach and location management), logical link management, and authentication and charging functions. The location register of the SGSN stores location information (e.g., current cell, current VLR) and user profiles (e.g., IMSI, IP address used in the packet data network) of all GPRS users registered with this SGSN.

Subscriber Identity Module (SIM) is part of a smart card ICC (Integrated Circuit Card), also known as SIM Cards, for mobile, telephony devices (such as computers) and mobile phones. SIM cards securely store the service-subscriber key (IMSI) used to identify a subscriber, plus a set of subscriber-specific and service provider-specific information. Most SIM cards are removable, and can allow a user to move a subscription from one device to another by moving the SIM. However, we expect to see new SIM form factors, based on non-removable chips, specifically for M2M in the near future.