Serial.begin(9800);
How are you selecting that baud rate in the Serial Monitor?
Serial1.begin(115200);
Is that the correct baud rate to talk to you GSM device? How IS the GSM device connected to the Arduino? Is the GSM device using pins 0 and 1?
sms application note:http://www.nskelectronics.com/files/sim900_sms_app_note.pdf)but i couldn't.i am using this code
It would be a lot better if YOU used the space key now and then. Your"link"doesn'tworkbecauseyoudidn'tleavespacesaroundit.