Improved OEM Features
1-10 AT Commands Reference Manual June 30, 20 08
Up to four simultaneous protocol connections.
Ability to pass data via the protocol stack using AT commands (command mode). This
relieves the terminal from switching the RS232 to "binary mode" and back to "command
mode".
Ability to use UDP and TCP simultaneously.
No need for protocol support from the terminal - only data sending and receiving.
Reduced memory utilization. The G24 manages the protocol stack and therefore saves
terminal memory.
Ability to open TCP connections, secured with SSL/TLS.
Ability to receive the incoming TCP connections.
Ability to accept IP connections only if the IP belongs to a defined IP white list.
Technical Description
Figure 1-1, “System Overview,” on page 1-5 displays the system overview which comprises the
following links and layers:
Physical layer links:
The terminal is connected to the G24 using a physical RS-232 connection.
The G24 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 G24.
After authentication, the G24 is linked to the GGSN using PPP protocol.
The GGSN is connected to its Internet service provider using some protocol.
TCP / UDP layer:
The G24 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 G24 software can manage these stacks internally. This enables the
G24 to relieve the terminal from the job of managing these protocols.
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.
Audio
Overview
The audio (digital and analog) feature in the G24 module involves three main issues: path (routes
the current input and output devices), gain (volume management) and algorithm. For more
information, refer to “Audio” on page 3-234.