Specifications

Telit GE864 and GC864

Product Description

80273ST10008A Rev. 3 - 10/02/06

AT#FRWL=1,"197.158.1.1","255.255.0.0"

5.1.4.2 Request the socket connection to be opened in listen

With the new command #SKTL (socket Listen) the TCP request to start listening for connection

requests is executed:

- GE864 / GC864 opens a listening socket on the port specified, waiting for incoming TCP

connections (depending on the parameter request) with the internet hosts

The parameters that shall be specified are the local port where packets shall be received, the type

of socket and the closing behavior.

5.1.4.3 Receiving connection requests

Once the connection request is received, the module reports an indication of connection with an

unsolicited code

+CONN FROM: <remote address>

- then connection is accepted and once it is up the module reports the code:

CONNECT

From this moment the data incoming in the serial port is packet and sent to the Internet host, while

the data received from the host is serialised and flushed to the Terminal Equipment.

Note that the connections request are FIRST screened in the firewall, then if they are accepted

they pass to the listening socket; therefore only hosts that are in the ACCEPT chain rules of the

firewall can induce a connection request, the other host requests will be silently discarded without

any indication to the remote host (for security reasons).

Once the connection is received and closed, the socket is not anymore in listen. If the application

needs again to be in listen, then it shall send again the socket listen #SKTL command.

NOTE: this command differently from the AT#SKTOP DOES NOT automate all the process of

activating the GPRS, if no GPRS is active the command reports ERROR; therefore before issuing

this command the GPRS shall be activated with AT#GPRS=1 command.

In the same manner, when disconnecting the #SKTL command does not close the GPRS context,

leaving it active for next connections until an AT#GPRS=0 command is issued or the network

requests a context closing.

5.1.4.4 Known limitations

The implementation of the EASY GPRS feature has the following known limitations:

- Only one socket can be opened at a time, no multiple socket connections can be made;

- Only one connection request can be accepted at a time, subsequent requests will be silently

discarded.

- Only the first GPRS context is associated with this feature;

- It is taken for granted that external processor will be able to handle at least a limited v.24

implementation: RTS, CTS and, highly recommended, DCD lines; this because software flow

control is not applicable to the feature;

- Due to the particularity of this feature, the flow control of both the directions uplink and

downlink is interlocked