diff --git a/src/Message/DPMCompleteResponse.php b/src/Message/DPMCompleteResponse.php
index eeef08cf..92975509 100644
--- a/src/Message/DPMCompleteResponse.php
+++ b/src/Message/DPMCompleteResponse.php
@@ -2,74 +2,9 @@
 
 namespace Omnipay\AuthorizeNet\Message;
 
-use Omnipay\Common\Message\AbstractResponse;
-use Omnipay\Common\Message\RedirectResponseInterface;
-
 /**
- * Authorize.Net DPM Complete Authorize Response
- * This is the result of handling the callback.
- * The result will always be a HTML redirect snippet. This gets
- * returned to the gateway, displayed in the user's browser, and a
- * redirect is performed using JavaScript and meta refresh (for backup).
- * We may want to return to the success page, the failed page or the retry
- * page (so the user can correct the form to try again).
+ * SIM and DPM both have identical needs when handling the notify request.
  */
-class DPMCompleteResponse extends SIMCompleteAuthorizeResponse implements RedirectResponseInterface
+class DPMCompleteResponse extends SIMCompleteAuthorizeResponse
 {
-    public function isSuccessful()
-    {
-        return isset($this->data['x_response_code'])
-            && static::RESPONSE_CODE_APPROVED === $this->data['x_response_code'];
-    }
-
-    /**
-     * If there is an error in the form, then the user should be able to go back
-     * to the form and give it another shot.
-     */
-    public function isError()
-    {
-        return isset($this->data['x_response_code'])
-            && static::RESPONSE_CODE_ERROR === $this->data['x_response_code'];
-    }
-
-    /**
-     * We are in the callback, and we MUST return a HTML fragment to do a redirect.
-     * All headers we may return are discarded by the gateway, so we cannot use
-     * the "Location:" header.
-     */
-    public function isRedirect()
-    {
-        return true;
-    }
-
-    /**
-    * We set POST because the default redirect mechanism in Omnipay Common only
-    * generates a HTML snippet for POST and not for the GET method.
-    * The redirect method is actually "HTML", where a HTML page is supplied
-    * to do a redirect using any method it likes.
-    */
-    public function getRedirectMethod()
-    {
-        return 'POST';
-    }
-
-    /**
-     * We probably do not require any redirect data, if the incomplete transaction
-     * is still in the user's session and we can inspect the results from the saved
-     * transaction in the database. We cannot send the result through the redirect
-     * unless it is hashed so the authorisation result cannot be faked.
-     */
-    public function getRedirectData()
-    {
-        return array();
-    }
-
-    /**
-     * The cancel URL is never handled here - that is a direct link from the gateway.
-     */
-    public function getRedirectUrl()
-    {
-        // Leave it for the applicatino to decide where to sent the user.
-        return;
-    }
 }
diff --git a/src/Message/SIMCompleteAuthorizeResponse.php b/src/Message/SIMCompleteAuthorizeResponse.php
index d1933fd7..b32cdd52 100644
--- a/src/Message/SIMCompleteAuthorizeResponse.php
+++ b/src/Message/SIMCompleteAuthorizeResponse.php
@@ -23,6 +23,15 @@ public function isSuccessful()
         return static::RESPONSE_CODE_APPROVED === $this->getCode();
     }
 
+    /**
+     * If there is an error in the form, then the user should be able to go back
+     * to the form and give it another shot.
+     */
+    public function isError()
+    {
+        return static::RESPONSE_CODE_ERROR === $this->getCode();
+    }
+
     public function getTransactionReference()
     {
         return isset($this->data['x_trans_id']) ? $this->data['x_trans_id'] : null;
diff --git a/tests/Message/DPMAuthorizeRequestTest.php b/tests/Message/DPMAuthorizeRequestTest.php
index 472c1187..1d4157d3 100644
--- a/tests/Message/DPMAuthorizeRequestTest.php
+++ b/tests/Message/DPMAuthorizeRequestTest.php
@@ -66,6 +66,7 @@ public function testSend()
         $this->assertSame('https://www.example.com/return', $redirectData['x_relay_url']);
     }
 
+    // Issue #16 Support notifyUrl
     public function testSendNotifyUrl()
     {
         $this->request->setReturnUrl(null);
diff --git a/tests/Message/DPMCompleteRequestTest.php b/tests/Message/DPMCompleteRequestTest.php
index 71c62b08..c22202b5 100644
--- a/tests/Message/DPMCompleteRequestTest.php
+++ b/tests/Message/DPMCompleteRequestTest.php
@@ -48,6 +48,7 @@ public function testSend()
                 'x_trans_id' => '12345',
                 'x_amount' => '10.00',
                 'x_MD5_Hash' => strtolower(md5('shhh' . 'user' . '12345' . '10.00')),
+                'omnipay_transaction_id' => '99',
             )
         );
         $this->request->setApiLoginId('user');
@@ -55,10 +56,19 @@ public function testSend()
 
         $this->request->setAmount('10.00');
 
+        $this->request->setReturnUrl('http://example.com/');
+
+        // Issue #22 Transaction ID in request is picked up from custom field.
+        $this->assertSame('99', $this->request->getTransactionId());
+
         $response = $this->request->send();
 
         $this->assertTrue($response->isSuccessful());
         $this->assertSame('12345', $response->getTransactionReference());
+        $this->assertSame(true, $response->isRedirect());
+        // CHECKME: does it matter what letter case the method is?
+        $this->assertSame('GET', $response->getRedirectMethod());
+        $this->assertSame('http://example.com/', $response->getRedirectUrl());
         $this->assertNull($response->getMessage());
     }
 
@@ -79,7 +89,7 @@ public function testSendWrongAmount()
         $this->request->setApiLoginId('user');
         $this->request->setHashSecret('shhh');
 
-        // In the callback, the merchant application sets the amount that
+        // In the notify, the merchant application sets the amount that
         // was expected to be authorised. We expected 20.00 but are being
         // told it was 10.00.
 
diff --git a/tests/Message/SIMCompleteAuthorizeRequestTest.php b/tests/Message/SIMCompleteAuthorizeRequestTest.php
index 64af2144..840e7424 100644
--- a/tests/Message/SIMCompleteAuthorizeRequestTest.php
+++ b/tests/Message/SIMCompleteAuthorizeRequestTest.php
@@ -42,17 +42,25 @@ public function testSend()
                 'x_trans_id' => $posted_trans_id,
                 'x_amount' => $posted_amount,
                 'x_MD5_Hash' => md5('shhh' . 'user' . $posted_trans_id . $posted_amount),
+                'omnipay_transaction_id' => '99',
             )
         );
         $this->request->setApiLoginId('user');
         $this->request->setHashSecret('shhh');
         $this->request->setAmount('10.00');
-        //$this->request->setTransactionId(99);
+        $this->request->setReturnUrl('http://example.com/');
+
+        // Issue #22 Transaction ID in request is picked up from custom field.
+        $this->assertSame('99', $this->request->getTransactionId());
 
         $response = $this->request->send();
 
         $this->assertTrue($response->isSuccessful());
         $this->assertSame($posted_trans_id, $response->getTransactionReference());
+        $this->assertSame(true, $response->isRedirect());
+        // CHECKME: does it matter what letter case the method is?
+        $this->assertSame('GET', $response->getRedirectMethod());
+        $this->assertSame('http://example.com/', $response->getRedirectUrl());
         $this->assertNull($response->getMessage());
     }
 }