Hi, we try to use modem to modem data communication by FXT009 with RS232 in China
but data communication vis GSM is not possible. Please someone had experiences with GSM network?
Please someone had experience with modem to modem via GPRS? Thank you
Hi,
May I clarify which carrier SIM you used and whether the problem is on GPRS or GSM data communication?
Thx
L
You should speak to your carrier to determine whether they allow that at all 
In most cases, GPRS devices are used in client/server styles - not peer-to-peer…
We like use GSM
the communication tests were made by SIM cards of China Mobile or China Unicom but data communication had not success.
Please have you idea of other solution point to point (with RS232 serial ports) in China with GSM or GPRS or other?
(DTE1 need to dial ATS123456789 the DTE2 and has data communication 9600b/s 8bit 1stop none)
You mean Circuit-Switched Data, CSD?
You should beware that many operators are now discontinuing CSD service - think very carefully before basing a new project on it! Seek professional local advice.
Were those cards specifically provisioned for CSD 
If you are just using general “consumer” phone SIMs, it is quite (very?) likely that they will not be provisioned for CSD!
Again, you should speak to someone knowledgeable in the local Data/M2M market - your SiWi Distributor should be able to help you.
The GSM communication (aka CSD, circuit switched data) is a common standard, which is supported on FXT009 but highly depends on network carrier and the SIM subscription.
It is true that CSD is phasing out and being replaced by packet switch (GPRS) as GPRS use less network resource and provide better speed.
Kindly check with local office of carrier (China Mobile and Unicom) to see if CSD service is supported on SIM card you used.
In case you want to switch to GPRS mode, you may use WIP library(or WIPSoft) to create a TCP socket between two FXT009.
Kindly refer to sample code comes with WIP library, tcp_client and tcp_server, or refer to WIPSoft AT command guide for detail.
One drawback using TCP/IP over CSD is the IP address assigned maybe different from time to time, specific mechanism needed to have that info available for both modems before the socket can be created.
Hope this help.
L
In general, you should assume that the IP address will be different each time the MS connects - unless you have specifically ordered a service which provides Static IP addresses.
Similarly, you should also assume that the IP address will be Private (ie, non-routable) - unless you have specifically ordered a service which provides Public IP addresses.
There are plenty of specialist M2M Service Providers (“MVNOs”) who will understand these issues and be able to supply you with suitable products.
Again, your local SiWi Distributor should be able to advise you.
Do not expect consumer phone service providers (high-street shops; websites) to understand these issues or provide suitable services