验证手机号

<script language="javascript">

 function checkmobile(tel){
     var reg = /^0?1[3|4|5|8][0-9]\d{8}$/;
     if (reg.test(tel)) {
        return true;
     }else{
        
        return false;
     };
 }

 function checkreg(dom){
       if(dom.phone.value ==''){
           alert('手机号不能为空！');
           dom.phone.focus();
           return false;
       }

       if(!checkmobile(dom.phone.value)){
          alert("手机号码有误~");
          dom.phone.focus();
          return false;
       }

       if(dom.yancode.value ==''){
           alert('验证码不能为空！');
           dom.yancode.focus();
           return false;
       }
       return true;
}
</script>

<form action="callService3.php"  method="post"  onSubmit="return checkreg(this);">