Try below code and see if you get a OK back from the phone true the Arduino serial monitor.
Arduino pin 0 and 1 connected to T68i pin 4 and 5 .
Try to switch cables both ways.
Let me know how it goes!
char incomingByte;
void setup() {
Serial.begin(9600);
delay(3000);
}
void loop() {
//check connection with phone
Serial.println("AT");
delay(3000);
// read phone reply if available
if (Serial.available() > 0) {
incomingByte = Serial.read(), BYTE;
// say what you got:
Serial.print("I received: ");
Serial.println(incomingByte);
}
}