The answer that I gave you before did not work ?
myself, I dont use library,
Library are changing too many parameters that you dont particularly understand , especially Github
i only use commades Hays, I spend a lot of time to understand them,
at the beginning:
include <SoftwareSerial.h>
include <string.h>
include <print.h>
include <serial.h>
//SoftwareSerial mySerial(RX, TX)
SoftwareSerial mySerial(50, 51); //OK
Serial.begin (9600);
mySerial.begin (9600);
mySerial.print ("\ r"); / / Send a newline
delay (500);
reset command, made ??that sometimes , especially after using Github
mySerial.print ("AT & F \ r"); / / Reset factory
delay (2000);
mySerial.print ("AT + CNMI = 2,1,0,0,0 \ r"); / / VERY IMPORTANT! ! !
delay (2000);
mySerial.println ("AT + CSCA = " 33660003000 \ "145 \ r"); / / To fit for your supplier and your country
delay (2000);
mySerial.println ("AT + CSAS"); / / save config
delay (200);
mySerial.print ("AT + CLIP = 1 \ r"); / / To view the phone number
delay (1000);
mySerial.print ("AT + IPR = 9600 \ r"); / / Baud rate to 9600
delay (1000);
mySerial.print ("AT + JEEC = 1 \ r"); / / For the extended errors
my favorite pages on the subject :
http://www.simcom.ee/modules/gsm-gprs/sim900/ for SIM900 AT Command Manual V1.09.pdf
GSM Equipment error codes explained
http://www.cooking-hacks.com/skin/frontend/default/cooking/pdf/SIM900_AT_Command_Manual.pdf
Dont get discouraged, it's dificult to start but then it's just fun
Henri