GPRS Modem stands for GPRS data transmission unit in the country at present actually GPRS Modem has a more clear agreement: GPRS Modem is designed for serial data transfer via GPRS network GPRS wireless devices.

Four core functions of GPRS Modem:

1. Integrated TCP / IP protocol stack
GPRS Modem encapsulated in the PPP dial-up protocol and TCP / IP protocol stack and an embedded operating system, from the hardware, it can be seen as a combination of embedded PC with a wireless GPRS MODEM; it has GPRS dial-up Internet access as well as TCP / IP data functional communication.

2. Provide bidirectional serial data conversion
GPRS Modem provides serial communication interfaces including RS232, RS485, RS422 belong to the common serial communication, and GPRS Modem in the design of most of the design data into a serial “transparent conversion” approach, that is to say GPRS Modem can convert the raw data into a serial port on the TCP / IP packets for transmission, without the need to change the original data communications. Therefore, GPRS Modem and may use a variety of serial communication device users to connect and does not need to make changes to the user equipment.

3. Supports automatic heartbeat, maintain a permanent online
One of the advantages of GPRS communications network to support GPRS terminal device is permanently online, so typical GPRS Modem is designed to support the permanent online feature, which requires Modem includes the automatic dial-up, using heartbeat packets are kept permanently online (as long when there is no data communication, mobile gateway will disconnect the Modem with the Centre, the heartbeat packet is MODEM and data center before the connection is disconnected to send a small packet to keep the connection is disconnected), supports automatic reconnection disconnection automatic redial features.

4. Support parameter configuration, permanent preservation
GPRS Modem as a communication device, its application is very extensive. In different applications, data center IP address and port number, serial port baud rate is different. Therefore, GPRS Modem should support parameter configuration, and the configuration parameters are stored within a good internal permanent storage device (typically FLASH EEPROM or the like). Upon power-up, it is automatically set in accordance with the parameters of good work.

GPRS Modem extensions:

More professional GPRS Modem also provides extended features, including: support for data center domain name resolution, support remote parameter configuration / remote firmware upgrade support remote SMS / wake-up call to support local serial firmware upgrade, provide messaging channel, providing Modem Online / offline level indication.

These extensions can enhance system reliability, and ease of use and maintenance of the user.