propart sim900 shield sim900 gprs / gsm wireless shield development board quad-band for arduino | elliott electronic supply
SIM800L V2.0 5V Wireless Quad Band GSM GPRS SIM 800 L Antenna Arduino - UK | eBay
SIM900 Quad Band GSM GPRS Shield Development Board from MMM999 on Tindie
A9 GSM/GPRS Module - DFRobot
Kadimendium Development Board Module Kit SIM900 Quad-Band Module GPRS/GSM Shield Development Board Module Fit for Arduino Mini-PC Barebone - Newegg.com
Amazon.com: Teyleten Robot SIM800C USB GSM GPRS Wireless Module Quad-Band, 850/900/1800/1900MHz, CH340T USB Chip Support 2G 3G 4G SIM Card USB Communication SMS Data Transmission with Antenna (SIM800C is New) : Electronics
Amazon.com: OSTENT Quad-Band GSM GPRS Modem with Wavecom Q24PLUS Module USB Interface TCP/IP SMS MMS : Electronics