[SOLVED] TCP\IP connection using sim 900 module problem

hello guys...
from past few days I'm working on TCP\IP protocol using sim 900 to develop GPRS based data logger system.
My aim is to develop client-server and server-client based n\w system.
For that purpose I've downloaded Desktop application "terminal.exe" and tune it in server mode to listen client, which is my sim 900 modem then after i fire at commands for sim 900 modem to force it in client mode to establish connection with server through server IP,
and it's working good and I'm able to send and receive data to server and from server.

Now consider second situation, I'm tuning my desktop application in client mode and force GPRS modem in server mode by sending at commands. The problem is when i try to connect client(application) to server(GPRS) through server IP(GPRS modem IP) then my client shows connection time out message!

can any one help me to find out problem,:bang:
I'll appreciate all precious comments:-D

GSM modems running a TCP/IP stack are usually behind a NAT (Network Address Translation) box so it is generally not possible to conect to a server running on a modem from the external internet

first of all thanx for reply,
Before post here , I've communicate two GSM modem in client and server mode and they are working as per my expectation and i got Bi-directional communication!
but I'm not getting connection from GPRS modem( in server mode) to web application(client mode) as I'm getting time out at client,
But as i told earlier, I've successfully established connection from client (GPRS MODEM) to server(web application) so what about that?
More-ever I've seen few product on internet having same application as i need here, so what about that?

https://vsblogs.wordpress.com/2013/11/28/tcp-connection-over-gprs-using-sim900-and-at-commands/
https://www.cooking-hacks.com/documentation/tutorials/arduino-gprs-gsm-quadband-sim900

what was the problem? what makes solved your problem? share here so it is helpful for others.

we all knows that gsm sim card have dynamic IP and it should change when GSM modem restarts,
when we tune GSM modem as client and any web application as server then web application(server) have static IP, so it is possible to send data and receive data to server and from.

Now if we make GSM modem as server and web application as client then, as i told earlier GSM have a dynamic IP so it is not registered to network so client (in this case web page) will not find it's IP and at last it show time out error!

so best idea is keep web page, having static IP as a server and GSM/GPRS modem as client to establish successful Bi-direction communication.

while in case of two GSM/GPRS modem they both have dynamic IP so they can effectively tune as client -server or server-client mode!

jitendrabaraiya said:

first of all thanx for reply,
Before post here , I've communicate two GSM modem in client and server mode and they are working as per my expectation and i got Bi-directional communication!
but I'm not getting connection from GPRS modem( in server mode) to web application(client mode) as I'm getting time out at client,
But as i told earlier, I've successfully established connection from client (GPRS MODEM) to server(web application) so what about that?
More-ever I've seen few product on internet having same application as i need here, so what about that?

Click to expand...

Hii Jitendrabaraiya can you please give me the at commands codes for the server client configuration b/w 2 modules as i am getting error in the same.
Thanks in Advance..