Amazon.com: OSTENT GSM/GPRS Dual-Band 900/1800MHz 2G Modem with Siemens MC52I Module USB Port Interface at Commands Bulk SMS MMS TCP/IP : Electronics
Amazon.com: OSTENT Quad-Band GSM GPRS Modem Pool with Wavecom Q24PLUS Module 8 Ports USB Interface Emulated COM/RS232 at Commands SMS MMS TCP/IP US Plug Power Adapter : Electronics
Usr-gprs232-730 Serial Rs232 Rs485 To 2g Gsm Modem Cellular 2g Gprs Gsm To Serial Modem Converter Dtu Flow Control Rts Cts Parts - Iot Accessories - AliExpress
GSM / GPRS Standard Modem Aerial - Magnetic Mounted | Comelit-PAC