This one will answer your question..
http://forum.arduino.cc/index.php?topic=226903.msg1642696#msg1642696
Your shield:
- UART Selection Switch: If the UART is selected, the GPS module will be connected to Arduino digital pins 0 and 1. If DLINE is selected, the GPS will be connected to digital pins 2 and 3 (default) or potentially any other digital pin. DLINE must be selected in order to upload code.
Use pins 2,3 for softwareserial
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