function formataTel(evt) {
var obj;
    if (navigator.appName.indexOf("Netscape") != -1) obj = evt.target;
    else obj = evt.srcElement;
    qtd = obj.value.length;
    if (qtd == 2) obj.value = "("+obj.value+")";
    if (qtd == 7) obj.value = obj.value+"-";
    if (qtd == 12 && evt.keyCode == 8) {
    character = tiraChar(obj.value, "-");
        obj.value = character.substring(0,7)+"-"+character.substring(7,12);
    }
    if (qtd == 13) {
    character = tiraChar(obj.value, "-");
    obj.value = character.substring(0,8)+"-"+character.substring(8,12);
}
}
function tiraChar(texto, caracter) {
var ret;
    for (i=0; i < texto.length; i++) {
    if (texto.substring(i, i+1) == caracter)
            ret = texto.substring(0, i)+texto.substring(i+1, texto.length);
    }
    return ret;
}