USB to GSM Module Quad-band GSM GPRS SIM800C for SMS Messaging With Antenna | eBay
NEW LandCell SMC-GPRS-GEN by Cal Amp SMC Wireless Quad Band GSM/GPRS Cal Amp, Circuit Boards, Condition_New
SIM900 Quad Band GSM GPRS Shield Development Board Geekcreit for Arduino - products that work with official Arduino boards
SIM800L V2.0 5V Wireless Quad Band GSM GPRS SIM 800 L Antenna Arduino - UK | eBay
Kadimendium Development Board Module Kit SIM900 Quad-Band Module GPRS/GSM Shield Development Board Module Fit for Arduino Mini-PC Barebone - Newegg.com