Modem GSM voice and GPRS (RS-232) 900/1800 - Cablematic
M1306B GSM Modem Wavecom Q2403 wireless industrial gsm gprs modem with rs232 com port support at command|modem gsm|modem wirelessmodem gprs - AliExpress
RS232/RS485 3G/2g GSM/GPRS Maestro M100 Modem with TCP/IP Smark Pack - China Modem and GSM Modem price | Made-in-China.com