怎么样才能先通过文字验证码，然后才进行手机号码验证？

我想实现必须先进行文字验证码验证，然后进行手机号码验证，就像下面这样的，应该怎么做？

代码：

<div class="form-group">
    <div class="col-md-12">
     <div class="input-group">
      <span class="input-group-addon" id="basic-addon2">验证码</span>
       <input name="verify" class="form-control" placeholder="请输入右边的验证码" type="text">
        <span class="input-group-btn">
        <img id='tpvercod' height="30" alt="验证码" src="{:U('Index/User/verifyImg',array())}" title="点击刷新">
        </span>                            
                        </div>
                    </div>
                </div>
                
                <div class="form-group">
                    <div class="col-md-12">
                        <div class="input-group">
                            <span class="input-group-addon" id="basic-addon1">手机号</span>
                            <input type="tel" name="user_mobi" id="user_mobi" value="" class="form-control" placeholder="请输入手机号" aria-describedby="basic-addon1" required="" autofocus="" />
                            <span class="input-group-btn">
                                <input id="btnGetVerCod" type="button" class="form-control btn btn-info pull-right" value="获取验证码">
                            </span>
                        </div>
                    </div>
                </div>

                <div class="form-group">
                    <div class="col-md-12">
                        <div class="input-group">
                            <span class="input-group-addon" id="basic-addon2">请输入</span>
                            <input type="text" name="vercod" id="vercod" value="" class="form-control" placeholder="请输入手机收到的验证码" />
                        </div>
                    </div>
                </div>
用了keyup后，每个字符都触发了ajax提交，应该怎么破~~~

$("#txtverify").keyup(function() {
                    var v_txt_ver_cod = $("#txtverify").val();
                    $.ajax({
                        url: "{:U('User/rcvTxtVerCod')}",
                        data: {
                            txt_ver_cod: v_txt_ver_cod,
                        },
                        type: "POST",
                        dataType: "json",
                        success: function(JSON) {
                            console.log(JSON);
                            if (JSON.result == "N") {
                                alert('N');
                            } else {
                                if (JSON.result == "Y") {
                                    console.log(JSON);
                                }
                            }
                        },
                        error: function(xhr, status, errorThrown) {
                            console.log("keyup err");
                            console.log(status);
                        }
                    }); //ajax end here