SM5100B only supports AT commands. Host uses AT commands to dial a number, send SMS, and GPRS connection.
SM5100B DTU supports both AT commanads mode and DTU mode. In DTU mode, LinkSprite provides a GUI utility to config the remote host IP address, port, and etc. After that, host can treat the DTU module as a normal serial port, and all raw data sent to serial port will appear at the remote host side without any extra work.