Switchfin now supports GSM1 module manufactured by Switchvoice Ltd.
It requires SIMCOM GSM firmware 1604B10SIM300M32_SST34HF3284 and above

Specifications:

• Single port GSM Interface
• Low cost solution
• Supported by IP01, IP02, IP04, IP08 and FX08 popular PBXs
• Quad-band GSM (850,900,1800, 1900 MHz)
• Transmit Power Class 1 (High Freq. Bands) and Class 4 (Low Freq. Bands)
• External Antenna
• Transmit Power Class 4 (2W) @ 850/900 MHz, Class 1 (1W) @ 1.8/1.9 GHz
• Design with power savings in mind - power consumption in SLEEP mode 3mA

To compile with enable GSM1 module just check the corresponding item in menuconfig interface.

Still we don't have support of the GSM1 configuration in the GUI 4.0. So you need to enable it manually.

1. Please insert your PIN protected SIM card in the GSM1 SIM holder.
   Note that the PBX behavior with GSM1 integrated is consistent only with SIM card in the GSM1
2. Boot the PBX and modify /etc/init.d/dahdi like this (change 1234 with your PIN number)
   
   start)  modprobe wcfxs SIM_pin="1234" opermode=$opermode;
3. Reboot the PBX
4. Execute /bin/dahdi_update.sh to get the GSM1 DAHDI channel configured
5. In GUI 4.0 assign analog trunk for the port you have put GSM1 in
6. Now you should be able to make GSM calls.