Amazon.com: OSTENT Quad-Band GSM GPRS Modem with Siemens MC55I Module COM/RS232/Serial Port at Commands TCP/IP SMS MMS Voice Call UK Plug Power Adapter : Electronics
Siemens MC35I terminal (GSM/GPRS-Modem) : Amazon.com.tr: Elektronik
6GK7242-7KX30-0XE0 Communications processor CP 1242-7 for connection of SIMATIC S7-1200 to GSM/