diff --git a/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml b/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml
index f8235bb..04c6fb7 100644
--- a/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml
+++ b/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml
@@ -54,7 +54,6 @@
                         <div asp-validation-summary="ModelOnly" class="text-danger mb-3"></div>
 
                         <!-- 隱藏欄位：系統傳入的資料 -->
-                        <input type="hidden" asp-for="InvoiceData.Identifier" />
                         <input type="hidden" asp-for="InvoiceData.TransDateTime" />
                         <input type="hidden" asp-for="InvoiceData.TransAmount" />
                         <input type="hidden" asp-for="InvoiceData.DeviceID" />
@@ -63,6 +62,21 @@
                         <input type="hidden" asp-for="InvoiceData.OrderID" />
                         <input type="hidden" asp-for="InvoiceData.TaxType" />
 
+                        @{
+                            if (string.IsNullOrWhiteSpace(Model.InvoiceData.Identifier))
+                            {
+                                Model.InvoiceData.Identifier = Model.CompanyTaxId;
+                            }
+                        }
+
+                        <div class="mb-3">
+                            <label asp-for="InvoiceData.Identifier" class="form-label">開發票者統編</label>
+                            <input asp-for="InvoiceData.Identifier"
+                                   class="form-control"
+                                   maxlength="8" />
+                            <span asp-validation-for="InvoiceData.Identifier" class="text-danger"></span>
+                        </div>
+
                         <div class="alert alert-info mb-4">
                             <strong>注意：</strong>以下三個選項只能填寫其中一個
                         </div>
diff --git a/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml.cs b/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml.cs
index da79cbb..d0da787 100644
--- a/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml.cs
+++ b/Altob.NtuInvoiceGateway/Pages/Invoice.cshtml.cs
@@ -7,20 +7,24 @@ using System.Text.Json;
 
 namespace Altob.NtuInvoiceGateway.Pages;
 
+[IgnoreAntiforgeryToken]  // 允許外部系統 POST JSON 請求
 public class InvoiceModel : PageModel
 {
     private readonly ILogger<InvoiceModel> _logger;
     private readonly IHttpClientFactory _httpClientFactory;
     private readonly CompanyInfo _companyInfo;
+    private readonly InvoiceApiOptions _invoiceApiOptions;
 
     public InvoiceModel(
         ILogger<InvoiceModel> logger,
         IHttpClientFactory httpClientFactory,
-        IOptions<CompanyInfo> companyInfo)
+        IOptions<CompanyInfo> companyInfo,
+        IOptions<InvoiceApiOptions> invoiceApiOptions)
     {
         _logger = logger;
         _httpClientFactory = httpClientFactory;
         _companyInfo = companyInfo.Value;
+        _invoiceApiOptions = invoiceApiOptions.Value;
     }
 
     [BindProperty]
@@ -35,55 +39,49 @@ public class InvoiceModel : PageModel
     public string DisplayTransDateTime { get; set; } = string.Empty;
     public string DisplayTransAmount { get; set; } = string.Empty;
 
-    public void OnGet(
-        string? identifier = null,
-        string? transDateTime = null,
-        string? transAmount = null,
-        string? deviceID = null,
-        string? email = null,
-        string? carrierID = null,
-        string? locationID = null,
-        string? carPlateNum = null,
-        string? orderID = null,
-        string? buyerIdentifier = null,
-        // string? loveCode = null,
-        string? taxType = null)
+    public void OnGet()
     {
-        // 從查詢字串接收系統轉頁傳來的資料
-        if (!string.IsNullOrEmpty(identifier))
-            InvoiceData.Identifier = identifier;
-        if (!string.IsNullOrEmpty(transDateTime))
-        {
-            InvoiceData.TransDateTime = transDateTime;
-            DisplayTransDateTime = transDateTime;
-        }
-        if (!string.IsNullOrEmpty(transAmount))
-        {
-            InvoiceData.TransAmount = transAmount;
-            DisplayTransAmount = transAmount;
-        }
-        if (!string.IsNullOrEmpty(deviceID))
-            InvoiceData.DeviceID = deviceID;
-        if (!string.IsNullOrEmpty(email))
-            InvoiceData.Email = email;
-        if (!string.IsNullOrEmpty(carrierID))
-            InvoiceData.CarrierID = carrierID;
-        if (!string.IsNullOrEmpty(locationID))
-            InvoiceData.LocationID = locationID;
-        if (!string.IsNullOrEmpty(carPlateNum))
-            InvoiceData.CarPlateNum = carPlateNum;
-        if (!string.IsNullOrEmpty(orderID))
-            InvoiceData.OrderID = orderID;
-        if (!string.IsNullOrEmpty(buyerIdentifier))
-            InvoiceData.BuyerIdentifier = buyerIdentifier;
-        // if (!string.IsNullOrEmpty(loveCode))
-        //     InvoiceData.LoveCode = loveCode;
-        if (!string.IsNullOrEmpty(taxType))
-            InvoiceData.TaxType = taxType;
+        // GET 方法保留為空，主要接收方式改為 POST JSON
     }
 
     public async Task<IActionResult> OnPostAsync()
     {
+        // 檢查是否為 JSON 請求（外部系統轉頁）
+        if (Request.ContentType?.Contains("application/json") == true)
+        {
+            try
+            {
+                // 從 Request Body 讀取 JSON 資料
+                using var reader = new StreamReader(Request.Body);
+                var jsonContent = await reader.ReadToEndAsync();
+
+                var jsonData = JsonSerializer.Deserialize<InvoiceRequest>(jsonContent, new JsonSerializerOptions
+                {
+                    PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+                    PropertyNameCaseInsensitive = true
+                });
+
+                if (jsonData != null)
+                {
+                    InvoiceData = jsonData;
+                    DisplayTransDateTime = InvoiceData.TransDateTime;
+                    DisplayTransAmount = InvoiceData.TransAmount;
+                    ModelState.Clear(); // ensure Razor uses the JSON payload values
+
+                    _logger.LogInformation("Received JSON redirect for OrderID: {OrderID}", InvoiceData.OrderID);
+                }
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Error parsing JSON request");
+                ErrorMessage = "接收轉頁資料時發生錯誤";
+            }
+
+            // 顯示表單讓用戶填寫
+            return Page();
+        }
+
+        // 處理表單提交
         // 保留發票資訊顯示
         DisplayTransDateTime = InvoiceData.TransDateTime;
         DisplayTransAmount = InvoiceData.TransAmount;
@@ -117,26 +115,54 @@ public class InvoiceModel : PageModel
             return Page();
         }
 
+        if (string.IsNullOrWhiteSpace(_invoiceApiOptions.Endpoint))
+        {
+            ErrorMessage = "未設定外部發票 API 的位址";
+            _logger.LogError("Invoice API endpoint is not configured");
+            return Page();
+        }
+
         try
         {
             // 呼叫 TODO API（這裡使用規格中的範例 API）
+            // http://192.168.110.72:22055/api/Intella/invoiceInfo
+            // {
+            //     "identifier": "12345678",
+            //     "transDateTime": "2026/01/08 12:00:00",
+            //     "transAmount": "30",
+            //     "deviceID": "test",
+            //     "locationID": "1",
+            //     "carPlateNum": "ABC1235",
+            //     "orderID": "260109_1",
+            //     "email": "",
+            //     "carrierID": "/ab12345",
+            //     "buyerIdentifier": "",
+            //     "taxType": "1",
+            //     "loveCode": ""
+            // }
             var httpClient = _httpClientFactory.CreateClient();
-            var jsonContent = JsonSerializer.Serialize(InvoiceData, new JsonSerializerOptions
+            var requestBody = JsonSerializer.Serialize(InvoiceData, new JsonSerializerOptions
             {
                 PropertyNamingPolicy = JsonNamingPolicy.CamelCase
             });
 
-            var content = new StringContent(jsonContent, Encoding.UTF8, "application/json");
+            var content = new StringContent(requestBody, Encoding.UTF8, "application/json");
 
-            // TODO: 替換為實際的 API 端點
-            var response = await httpClient.PostAsync("YOUR_API_ENDPOINT_HERE", content);
+            var response = await httpClient.PostAsync(_invoiceApiOptions.Endpoint, content);
 
             var responseContent = await response.Content.ReadAsStringAsync();
             var apiResponse = JsonSerializer.Deserialize<InvoiceResponse>(responseContent, new JsonSerializerOptions
             {
-                PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+                PropertyNameCaseInsensitive = true
             });
 
+            if (!response.IsSuccessStatusCode)
+            {
+                ErrorMessage = $"提交失敗：{apiResponse?.msg ?? response.StatusCode.ToString()}";
+                _logger.LogWarning("Invoice submission failed with HTTP {StatusCode} for OrderID: {OrderID}", response.StatusCode, InvoiceData.OrderID);
+                return Page();
+            }
+
             if (apiResponse?.msgCode == "0000")
             {
                 SuccessMessage = "發票資訊提交成功！";
diff --git a/Altob.NtuInvoiceGateway/Pages/TestPostInvoice.cshtml b/Altob.NtuInvoiceGateway/Pages/TestPostInvoice.cshtml
index 22c7fa9..dabe75c 100644
--- a/Altob.NtuInvoiceGateway/Pages/TestPostInvoice.cshtml
+++ b/Altob.NtuInvoiceGateway/Pages/TestPostInvoice.cshtml
@@ -1,4 +1,5 @@
 @page
+@model TestPostInvoiceModel
 @{
     ViewData["Title"] = "POST 轉頁測試";
     Layout = null;
@@ -25,12 +26,20 @@
                     <div class="row mb-3">
                         <div class="col-md-6">
                             <label class="form-label">開發票者統編 (Identifier) *</label>
-                            <input type="text" class="form-control" name="InvoiceData.Identifier" value="12345678" required>
+                            <input type="text"
+                                   class="form-control"
+                                   name="InvoiceData.Identifier"
+                                   value="@(string.IsNullOrWhiteSpace(Model.CompanyTaxId) ? "" : Model.CompanyTaxId)"
+                                   required>
                             <small class="text-muted">8位數字</small>
                         </div>
                         <div class="col-md-6">
                             <label class="form-label">發票交易日期 (TransDateTime) *</label>
-                            <input type="text" class="form-control" name="InvoiceData.TransDateTime" value="2024-01-15 14:30:00" required>
+                            <input type="text"
+                                   class="form-control"
+                                   name="InvoiceData.TransDateTime"
+                                   value="@Model.CurrentTransDateTime"
+                                   required>
                         </div>
                     </div>
 
@@ -42,26 +51,26 @@
                         </div>
                         <div class="col-md-6">
                             <label class="form-label">設備代號 (DeviceID) *</label>
-                            <input type="text" class="form-control" name="InvoiceData.DeviceID" value="DEVICE001" required>
+                            <input type="text" class="form-control" name="InvoiceData.DeviceID" value="NtuInvoiceGateway" required>
                         </div>
                     </div>
 
                     <div class="row mb-3">
                         <div class="col-md-6">
                             <label class="form-label">停車場站代號 (LocationID) *</label>
-                            <input type="text" class="form-control" name="InvoiceData.LocationID" value="A" maxlength="1" required>
+                            <input type="text" class="form-control" name="InvoiceData.LocationID" value="1" maxlength="1" required>
                             <small class="text-muted">1個字元</small>
                         </div>
                         <div class="col-md-6">
                             <label class="form-label">車牌號碼 (CarPlateNum) *</label>
-                            <input type="text" class="form-control" name="InvoiceData.CarPlateNum" value="ABC1234" required>
+                            <input type="text" class="form-control" name="InvoiceData.CarPlateNum" value="9M1234" required>
                         </div>
                     </div>
 
                     <div class="row mb-3">
                         <div class="col-md-6">
                             <label class="form-label">訂單編號 (OrderID) *</label>
-                            <input type="text" class="form-control" name="InvoiceData.OrderID" value="ORDER20240115001" required>
+                            <input type="text" class="form-control" name="InvoiceData.OrderID" value="@Model.CurrentOrderNo" required>
                         </div>
                         <div class="col-md-6">
                             <label class="form-label">稅別 (TaxType) *</label>
@@ -114,6 +123,21 @@
                     </ul>
                 </div>
 
+                <hr class="my-4">
+
+                <div class="card border-primary">
+                    <div class="card-header bg-primary text-white">
+                        <h5>JSON POST 測試（符合規格要求）</h5>
+                    </div>
+                    <div class="card-body">
+                        <p class="text-success"><strong>✓ 此方式符合英特拉規格：Method: POST, 資料格式: JSON</strong></p>
+                        <button type="button" class="btn btn-primary btn-lg w-100" onclick="testJsonPost()">
+                            發送 JSON POST 請求到發票頁面
+                        </button>
+                        <div id="jsonResult" class="mt-3"></div>
+                    </div>
+                </div>
+
                 <hr>
 
                 <div class="card bg-light">
@@ -127,5 +151,55 @@
     </div>
 
     <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/js/bootstrap.bundle.min.js"></script>
+    <script>
+        async function testJsonPost() {
+            const resultDiv = document.getElementById('jsonResult');
+            resultDiv.innerHTML = '<div class="alert alert-info">發送中...</div>';
+
+            const form = document.querySelector('form');
+            if (!form) {
+                resultDiv.innerHTML = '<div class="alert alert-danger">找不到表單元素</div>';
+                return;
+            }
+
+            const formData = new FormData(form);
+            const jsonData = {
+                identifier: formData.get('InvoiceData.Identifier')?.toString() ?? '',
+                transDateTime: formData.get('InvoiceData.TransDateTime')?.toString() ?? '',
+                transAmount: formData.get('InvoiceData.TransAmount')?.toString() ?? '',
+                deviceID: formData.get('InvoiceData.DeviceID')?.toString() ?? '',
+                email: formData.get('InvoiceData.Email')?.toString() ?? '',
+                carrierID: formData.get('InvoiceData.CarrierID')?.toString() ?? '',
+                locationID: formData.get('InvoiceData.LocationID')?.toString() ?? '',
+                carPlateNum: formData.get('InvoiceData.CarPlateNum')?.toString() ?? '',
+                orderID: formData.get('InvoiceData.OrderID')?.toString() ?? '',
+                buyerIdentifier: formData.get('InvoiceData.BuyerIdentifier')?.toString() ?? '',
+                loveCode: '',
+                taxType: formData.get('InvoiceData.TaxType')?.toString() ?? ''
+            };
+
+            try {
+                const response = await fetch('/Invoice', {
+                    method: 'POST',
+                    headers: {
+                        'Content-Type': 'application/json'
+                    },
+                    body: JSON.stringify(jsonData)
+                });
+
+                if (response.ok) {
+                    // JSON POST 成功，直接顯示返回的 HTML 頁面
+                    const html = await response.text();
+                    document.open();
+                    document.write(html);
+                    document.close();
+                } else {
+                    resultDiv.innerHTML = `<div class="alert alert-danger">請求失敗: ${response.status}</div>`;
+                }
+            } catch (error) {
+                resultDiv.innerHTML = `<div class="alert alert-danger">發生錯誤: ${error.message}</div>`;
+            }
+        }
+    </script>
 </body>
 </html>
diff --git a/Altob.NtuInvoiceGateway/Pages/TestPostInvoice.cshtml.cs b/Altob.NtuInvoiceGateway/Pages/TestPostInvoice.cshtml.cs
index c58b5d0..c7ee67e 100644
--- a/Altob.NtuInvoiceGateway/Pages/TestPostInvoice.cshtml.cs
+++ b/Altob.NtuInvoiceGateway/Pages/TestPostInvoice.cshtml.cs
@@ -1,9 +1,23 @@
+using System;
+using Altob.NtuInvoiceGateway.Models;
 using Microsoft.AspNetCore.Mvc.RazorPages;
+using Microsoft.Extensions.Options;
 
 namespace Altob.NtuInvoiceGateway.Pages;
 
 public class TestPostInvoiceModel : PageModel
 {
+    public string CompanyTaxId { get; }
+    public string CurrentTransDateTime { get; }
+    public string CurrentOrderNo { get; }
+
+    public TestPostInvoiceModel(IOptions<CompanyInfo> companyInfo)
+    {
+        CompanyTaxId = companyInfo.Value.TaxId;
+        CurrentTransDateTime = DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss");
+        CurrentOrderNo = DateTime.Now.ToString("ORDERyyyyMMddHHmmssfff");
+    }
+
     public void OnGet()
     {
     }
diff --git a/Altob.NtuInvoiceGateway/Program.cs b/Altob.NtuInvoiceGateway/Program.cs
index cd178e2..efa201d 100644
--- a/Altob.NtuInvoiceGateway/Program.cs
+++ b/Altob.NtuInvoiceGateway/Program.cs
@@ -7,6 +7,8 @@ builder.Services.AddHttpClient();
 // Configure company info
 builder.Services.Configure<Altob.NtuInvoiceGateway.Models.CompanyInfo>(
     builder.Configuration.GetSection("CompanyInfo"));
+builder.Services.Configure<Altob.NtuInvoiceGateway.Models.InvoiceApiOptions>(
+    builder.Configuration.GetSection("InvoiceApi"));
 
 var app = builder.Build();
 
@@ -28,4 +30,4 @@ app.MapStaticAssets();
 app.MapRazorPages()
     .WithStaticAssets();
 
-app.Run();
\ No newline at end of file
+app.Run();
diff --git a/Altob.NtuInvoiceGateway/appsettings.Development.json b/Altob.NtuInvoiceGateway/appsettings.Development.json
index 770d3e9..8a08e7c 100644
--- a/Altob.NtuInvoiceGateway/appsettings.Development.json
+++ b/Altob.NtuInvoiceGateway/appsettings.Development.json
@@ -5,5 +5,8 @@
       "Default": "Information",
       "Microsoft.AspNetCore": "Warning"
     }
+  },
+  "InvoiceApi": {
+    "Endpoint": "http://192.168.110.72:22055/api/Intella/invoiceInfo"
   }
 }
diff --git a/Altob.NtuInvoiceGateway/appsettings.json b/Altob.NtuInvoiceGateway/appsettings.json
index 39cdfe6..6dd2c9f 100644
--- a/Altob.NtuInvoiceGateway/appsettings.json
+++ b/Altob.NtuInvoiceGateway/appsettings.json
@@ -9,5 +9,8 @@
   "CompanyInfo": {
     "Name": "國立台灣大學臨時停車場",
     "TaxId": "18384226"
+  },
+  "InvoiceApi": {
+    "Endpoint": "http://192.168.110.72:22055/api/Intella/invoiceInfo"
   }
 }