Product Features
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2.1.2.3 Technical Description
The following picture describes
Figure 2. TCP/IP
TCP/IP comprises the following links and layers:
Physical layer links:
• The terminal is connected to the g20 using a physical RS-232 connection.
• The g20 is connected to the GGSN using a GPRS link.
• The GGSN is connected to the Internet via some sort of physical connection (usually telephone or cable).
Point-to-point layer links:
• AT command protocol is used to transfer data between the terminal and the g20.
• After authentication, the g20 is linked to the GGSN using PPP protocol.
• The GGSN is connected to its Internet service provider using some protocol.
TCP / UDP layer:
• The g20 can transfer data with the WEB using either TCP/IP or UDP/IP protocols.
• The protocol stacks in the terminal or in the OEM must be managed when using TCP/IP or UDP/IP protocols. The g20
software can manage these stacks internally. This enables the g20 to relieve the terminal from the job of managing these
protocols.
2.1.3 Audio
2.1.3.1 Overview
The audio feature in the g20 module involves three main issues: path (routes the current input and output devices), gain (volume
management) and algorithm.
Note
Currently, the embedded TCP/IP feature may be used only for mobile-initiated connections. The embedded TCP/
IP feature cannot listen on a port for incoming connections.
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