c++ - Arduino - making a ringing tone but its not accurate -

arduino, trying make ring tone (like brrr brrr, brrr brrr, old common telephone ring tone), not close yet. can show me how it?

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