Im working on a GPS tracker, so i have working the gsm shield, i have working the GPS shield, but, in the moment i try to mix the sketch stops working just after cel, why is that? how i fix it?
gps.begin(9600); // the SoftSerial baud rate
Serial.begin(9600); // the Serial port of Arduino baud rate.
cel.begin(19200);
According to the documentation, the SoftwareSerial library can only support one serial port that is reading at a time. http://arduino.cc/en/Reference/SoftwareSerial
You probably should go to a micrprocessor that has at least three hardware serial ports, such as the Mega 2560, the Due, the DigiX all have support for 4 hardware serial ports, and the Teensy 3.0/3.1 has support for 3 hardware serial ports. To use the hardware serial ports, you use Serial0/Serial1/Serial2/Serial3 on the Mega/Due/DigiX, and Serial1/Serial2/Serial3 on the Teensy 3.x. Note, in these machines pins 0/1 are not connected to the USB, and you continue to use Serial to write to the USB connection.