I am testing SIM908C Module but facing an issue. I can send all the AT Commands except CTRL-Z Char. So that I can not able to send SMS or GPRS Data. I tested with both 115200 and 9600 Baud. For terminal Client Application, I tested Hyper-Terminal, Putty and DockLight. But problem remains constant.
Ctrl-Z = 0x1A (SUB character).
In Docklight there is no shortcut for 0x1A, you can check this from Tools->Options->Control Character Shortcuts. You can assign a shortcut of your own (not necessarily CTRL+Z, but anything you like).
Also there is the option to directly send the hex value 0x1A or decimal 26.