GPRS tutorial - what is GPRS?

The General Packet Radio Service (GPRS) network is an "always on", private network for data. It uses the existing GSM network to transmit and receive TCP/IP based data to and from GPRS mobile devices. Private IP addresses are typically dynamically assigned within the network to mobile devices. However, Access Point Names (APN's) provide a gateway route to other networks such as the Internet, WAP services or private corporate networks. Firewalls typically reside at the APN to isolate the public and private networks. IP addresses allocated to mobile GPRS devices are therefore not addressable from outside the GPRS network (e.g. from the Internet) without specialised services or infrastructure.

GPRS tutorial - GPRS elements diagram

GPRS tutorial - Public Internet access to GPRS devices

GPRS devices are not addressable from the internet

The Internet and GPRS are designed for client driven applications and are therefore directly supported by a gprs router or gprs modems dial out mode of operation. Due to APN firewalls, remote GPRS server devices can only be addressed by a private network solution or via more complex VPN technology.

GPRS tutorial - Private network access to GPRS devices

Although client GPRS devices can communicate with ease over Public and Private networks, GPRS server devices require a static IP address. Network Operators offer private APN's to corporate networks over Leased Lines or VPN's, where IP address assignment is managed by the customer's corporate Network e.g. using a radius server. Alternatively, Wireless Operators in some countries offer private APN's with static IP address support thereby creating customers their own private network within the GPRS network. These are supported by the GPRS modem or GPRS routers "Always on" mode of operation.

Note: Contact your local Wireless Operator to investigate the options available to you.

GPRS tutorial - GPRS mobile device

There are a number of GPRS devices, each of which can offer GSM services too, such as voice calls and SMS.

• A GPRS Mobile Phone
• A GPRS Radio Card for a PC
• A Hand held PC with an in-built GPRS Mobile
• A remote machine enabled with a Comtech GPRS M2M device.

GPRS tutorial - GPRS classes of GPRS device

There are 3 classes of GPRS device being developed, of which only class B is currently available: -

• Class A - Operates in GSM and GPRS modes at the same time, and hold simultaneous voice and data sessions.
• Class B - Operates in GSM and GPRS modes at the same time, and but cannot hold simultaneous calls.
• Class C - Can be active in either GSM or GPRS mode, but not at the same time

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