There seems to be a company selling off these:
They are 10 Euro GSM/UMTS gateways, and at least mine was the “DATA” version which claims to support Fax and data calls via a prefix to the number. (01 for fax, 02 for data) Mine even came with a SIM-card.
I guess data calls are supported only using CSD but I can’t find a carrier who support that anymore.
Too bad the shipment is a bit expensive (50 Euro for where I am).
Interesting hardware. Could you open it up and take a look inside (chipset, etc.)?
http://www.clarke-3.de/gsm_adapter/
Seems to mostly be a GSM/UMTS module, an ATMega 128 and a Modem IC.
Thanks! Knowing that it’s a SIM5320E module inside is very useful, as you can find the datasheet and command manual for that:
I think I’ll get 2 of those.
Yes those SIMCOM chips are fairly popular. I’ve worked with them in the past. Overall it seems like the ATMega is controlling the logic of the whole thing. It probably first, either directly or with the help of the modem, generates the tones and decodes the DTMF, then either sends the call to the IMCOM directly or first to the Modem where it will be demodulated. The data then will be sent via CSD.
IFAIR the 2N is a Czech company and they have long history of making products like this, in many configurations. I own 2N BRI Lite ISDN GSM Gateway and these also can be found for cheap sometimes.
the manual states [at least] Fax is only over 2G / CSD.
You can operate it such devices in a SDR based GSM network using osmo-trx + osmo-bts-trx; we do support CSD for more than a year now.
