Iphone

I need to connect 2 uC's and both are connected via RS232 to an Enfora Spider SA-G modem. The uC's don't have any PPP stack. I just need to send plain ASCII information from on uC to another. Can this be done? I have already done it with SMS, but we would like to change to GPRS.

Another problem is that the IP are asigned dynamicaly. If it is not possible to use uC's, how can connect 2 PC´s and just send ASCII text between them, because every time I connect, I have different IP.

Iphone

You can view GPRS as very much the same as dialing any other ISP.

When you dial *99# you will start a PPP session, so your uC needs both a PPP stack and an IP stack, try Embedded Ethernet for a open source OS that may be of use.

There is no way around this, one way or another you need an IP stack to use GPRS.

However there is another option, various GSM modules include a built in IP stack and the ability for you to load your own application into the module to make use of it, some examples are:-

Nokia 12
Sony Ericsson GR47
Various wavecom modules.

To connect your 2 pc's just use windows dial up networking and set the number to dial to *99#.
(After you've set the APN using hyperterminal and AT+CGDCONT=1,"IP","<APN provided>")