var timeInterval = 300;
var divPrefix = 'phone_char';
var highlightColor = 'red';
var originalColor = 'black';

function startHighlightScroll(index) {
    var character = document.getElementById(divPrefix + index);

    if (character == null) {
        return;
    }

    character.style.color = highlightColor;

    index++;

    character = document.getElementById(divPrefix + index);
    if (character == null) {
        setTimeout('revertToOriginalColor()', timeInterval);
        return;
    }

    setTimeout('startHighlightScroll(' + index + ')', timeInterval);
}

function revertToOriginalColor() {
    var i = 1;
    var character = document.getElementById(divPrefix + i);
    while (character != null) {
        character.style.color = originalColor;
        i++;
        var character = document.getElementById(divPrefix + i);
    }

    setTimeout('startHighlightScroll(1)', timeInterval);

}