This is a GPS/GPRS/GSM shield from DFRobot. This shield with a Quad-band GSM/GPRS engine works on frequencies EGSM 900MHz/DCS 1800MHz and GSM850 MHz/PCS 1900MHz. It also supports GPS technology for satellite navigation. It's possible for your robot and control system to send messages and use the GSM network.
 
It is controlled via AT commands (GSM07.07 ,07.05 and SIMCOM enhanced AT Commands). And the design of this shield allows you to drive the GSM & GPS function directly with the computer and the Arduino Board. It includes a high-gain SMD antenna for GPS and a flexible GSM antenna 8.5cm ( U.FL connector ).
 
This GPS/GPRS/GSM shield uses an embedded SIM908 chip from SIMCom. Featuring an industry-standard interface and GPS function, the combination of both technologies allows items, vehicles and people to be tracked seamlessly at any location and anytime with signal coverage.
 

SPECIFICATION

    Power supply: 6-12v
    Low power consumption (100mA@7v ― GSM mode)
    Quad-Band 850/900/18001900MHz
    GPRS multi-slot class 10
    GPRS mobile station class B
    Compliant to GSM phase 2/2+
    Class 4 (2 W @ 850/900 MHz)
    Class 1 (1 W @ 1800/1900MHz)
    Control via AT commands(GSM07.07 ,07.05 and SIMCOM enhanced AT Commands)
    Support GPS technology for satellite navigation
    Embeded high-gain SMD antennas for GPS & GSM
    Directly support 4*4 button pad
    USB/Arduino control switch
    Programmable switch for Arduino
    LED indicators for power supply, network states and working status
    Board Surface:Immersion Gold
    Switches:
        S1 -- Programming mode / Communication mode
        S2 -- Controlling interface: USB / Arduino
    Interfaces:
        Embedded SIM card holder
        Speaker & Mic Jack socket
    Size: 81x70mm

    Specifications for SMS via GSM / GPRS
        Point-to-point MO and MT
        SMS cell broadcast
        Text and PDU mode

    Specification for GPS
        Receiver 42 channels, GPS L1 C/A code, High-performance STE engine
        Sensitivity:
            Tracking: -160 dBm
            Cold starts: -143 dBm
        Time-To-First-Fix:
            Cold starts: 30s (typ.)
            Hot starts: 1s (typ.)
        Accuracy:Horizontal position: <2.5m CEP
        Power consumption (GSM engine in idle mode):Acquisition 77mA,Tracking 76mA

• Wiki
• Schematic        
• SiRF NMEA Protocol      
• AT Command manual      
• SIM908_SIM548C_ATC_Comparison       
• SIM908 Datasheet      
• SIM908 Product Page  
• Youtube Video               
• Test library for Leonardo based boards