Arduino - making a ringing tone but its not accurate

Question

Arduino, i am trying to make ring tone (like brrr brrr, brrr brrr, old common telephone ring tone), but i am not even close to it yet. Can anyone show me how you do it?

void play_on() { // this should play exact telephony ring tone, but how?
  for(int i=0; i <50; i++) {
    tone(2, i+900, i+10);  
    delay(60);              
    noTone(2);

  }    
}