What's the purpose of the jumper on the GPRS shield 1.2?

Exactly! Is it to change the pin assignments? If so, which position does what?

I’d like to use the shield with a Netduino Plus on COM2 (RX on Pin 2, TX on Pin 3, RTS on Pin 7 and CTS on Pin 8), enabling CTS/RTS flow control. Is this possible? If so, how should the jumpers be set?

Thanks for taking the time to reply!