diff --git a/src/Api/Ip.php b/src/Api/Ip.php
index 80d4ab0..35294d1 100644
--- a/src/Api/Ip.php
+++ b/src/Api/Ip.php
@@ -29,13 +29,13 @@ class Ip extends HttpApi
      *
      * @return IndexResponse|ResponseInterface
      */
-    public function index(bool $dedicated = false)
+    public function index(?bool $dedicated = null)
     {
-        Assert::boolean($dedicated);
-
-        $params = [
-            'dedicated' => $dedicated,
-        ];
+        $params = [];
+        if (null !== $dedicated) {
+            Assert::boolean($dedicated);
+            $params['dedicated'] = $dedicated;
+        }
 
         $response = $this->httpGet('/v3/ips', $params);
 
diff --git a/tests/Api/Ip.php b/tests/Api/Ip.php
new file mode 100644
index 0000000..bca3166
--- /dev/null
+++ b/tests/Api/Ip.php
@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Copyright (C) 2013 Mailgun
+ *
+ * This software may be modified and distributed under the terms
+ * of the MIT license. See the LICENSE file for details.
+ */
+
+namespace Mailgun\Tests\Api;
+
+use GuzzleHttp\Psr7\Response;
+use Mailgun\Api\Ip;
+use Mailgun\Model\Ip\IndexResponse;
+
+class IpTest extends TestCase
+{
+    protected function getApiClass()
+    {
+        return Ip::class;
+    }
+
+    public function testIndexAll()
+    {
+        $this->setRequestMethod('GET');
+        $this->setRequestUri('/v3/ips');
+        $this->setHttpResponse(new Response(200, ['Content-Type' => 'application/json'], <<<'JSON'
+{
+  "items": ["192.161.0.1", "192.168.0.2"],
+  "total_count": 2
+}
+JSON
+        ));
+
+        $api = $this->getApiInstance();
+        /** @var IndexResponse $response */
+        $response = $api->index(null);
+        $this->assertInstanceOf(IndexResponse::class, $response);
+        $this->assertEquals(2, $response->getTotalCount());
+        $this->assertEquals('192.161.0.1', $response->getItems()[0]);
+        $this->assertEquals('192.168.0.2', $response->getItems()[1]);
+    }
+    
+    public function testIndexOnlyDedicated()
+    {
+        $this->setRequestMethod('GET');
+        $this->setRequestUri('/v3/ips?dedicated=1');
+        $this->setHttpResponse(new Response(200, ['Content-Type' => 'application/json'], <<<'JSON'
+{
+  "items": ["192.161.0.1"],
+  "total_count": 1
+}
+JSON
+        ));
+
+        $api = $this->getApiInstance();
+        /** @var IndexResponse $response */
+        $response = $api->index(true);
+        $this->assertInstanceOf(IndexResponse::class, $response);
+        $this->assertEquals(1, $response->getTotalCount());
+        $this->assertEquals('192.161.0.1', $response->getItems()[0]);
+    }
+    
+    public function testIndexOnlyShared()
+    {
+        $this->setRequestMethod('GET');
+        $this->setRequestUri('/v3/ips?dedicated=0');
+        $this->setHttpResponse(new Response(200, ['Content-Type' => 'application/json'], <<<'JSON'
+{
+  "items": ["192.168.0.2"],
+  "total_count": 1
+}
+JSON
+        ));
+
+        $api = $this->getApiInstance();
+        /** @var IndexResponse $response */
+        $response = $api->index(false);
+        $this->assertInstanceOf(IndexResponse::class, $response);
+        $this->assertEquals(1, $response->getTotalCount());
+        $this->assertEquals('192.168.0.2', $response->getItems()[0]);
+    }
+}