You understranding is correct that for dynamic allocated IP address to module, its a challenge. There are multiple ways to solve the problem depending upon the application/business needs:
1. If server needs to reach out module, it can send the SMS with shoulder tap message
2. Setup the VPN between the operator network and server so that module can get the STATIC IP address.
3. Selecting TCP over UDP
4. Keeping the connective alive forever
In a previous thread on TCP vs UDP, "kopeister" may have covered this:
"On most GPRS networks TCP is higher priorized and handled better than UDP. I have seen situations on some networks where all small UDP packets were dropped by the carrier."
Hope it helps,
What about to use a simple "GET" ?
GET / http://yourserver.com/upload/text.test.php...67,290610,12503
For that there is no fixed IP needed. Normaly any "stupid" SIM card will support this.
here is the my solution;
after some research I decided to use e-mails to send IPs of modules.
module sends e-mail after gprs context is active, IP address is in the e-mail. when I load the page, I am reading mails using pop3 feature and I am writing IPs to a xml file, when I want to establish a connection, my program gets IP from xml and put it to necessary place, and sends string to the module.
Just now found this very usefull site.
Don't know if this post helps.. but here it goes my contribution.
I had a similar problem too... working with Telit modems also.
Instead of sending an email with the IP (I found a good idea anyhow!) I first start the modem as client, and connect to IT computer/server I kwnow.
It's then server's job to inpair my IP with the equipment I'm connected to, and store it in a database.
This connection is then closed and modem starts acting like a server itself.
The IT computer whenever wants to comunicate knows my IP.
Any change of IP will be tracked by the modem (network operators sometimes force to it) and will restart the process all again.
What I found more difficult, was to keep the PDP context active/alive. Sometimes after long periods with no comunnicatios, my modem (as a server) still has an IP but the network cannot reach it. The solution was to make periodic pings from the modem to the network.