Hi Everybody ! Is there anybody who has experience in communication with AB SLC500 or SIEMENS S7-300 via GSM modem on the processor side and analog modem on the caller side. If is, I would like to know how to set the units and the communication. I got for testing a Wawecom WMOD2 GSM modem, I can call with this an analog modem on the PLC side, but not other way. I need this thing for remote diagnostic and program upload, download. Any help or idea would be appreciated. Thanks Jozsef Sipos ZENON Systems Kft.