I am reading the GSM shield page http://arduino.cc/en/Guide/ArduinoGSMShield. There is a photo about the board taken directly above. The text on photo says: GSM TX (pin3) but it easy to see on the photo that it is really RX. The other pin is wrong also. The whole Arduino site seems confusing these.
I am trying to start Itead 3G modem to communicate with the MEGA, but it is difficult to know what are the RX and TX pins really. They are crossed on the Itead Board. I can say now that Itead's documentation is not very helpful either. Because of all this I have to trace the connections with a multimeter. I would rather do something else at Friday night.