<p>電話號碼: <input type="text" id="phone_n" name="phone_n" valid="true" class="txt tt160"><span class="in_block"></span></p> <p>電話號碼: <input type="text" id="phone_n" name="phone_n" valid="true" class="txt tt160"><span class="in_block"></span></p>
<p>電話號碼: <input type="text" id="phone_n" name="phone_n" valid="true" class="txt tt160"><span class="in_block"></span></p>
$("input[name=phone_n][value="+phoneNumber+"]").attr("valid","false");