diff --git a/src/Utils/Url.php b/src/Utils/Url.php
index 2903ca9..99d7a93 100644
--- a/src/Utils/Url.php
+++ b/src/Utils/Url.php
@@ -10,6 +10,11 @@ class Url
 {
     public static function baseUrl(): string
     {
+        $envBaseUrl = getenv('GREENSMS_BASE_URL');
+        if (is_string($envBaseUrl)) {
+            return $envBaseUrl;
+        }
+
         return BASE_URL;
     }
 
diff --git a/tests/EnvTest.php b/tests/EnvTest.php
index 25e94f7..4fd1b62 100644
--- a/tests/EnvTest.php
+++ b/tests/EnvTest.php
@@ -1,7 +1,5 @@
 <?php
-
-
-
+use GreenSMS\Http\RestException;
 use GreenSMS\Tests\Utility;
 use GreenSMS\GreenSMS;
 use GreenSMS\Tests\TestCase;
@@ -21,4 +19,16 @@ public function testCanFetchLookup()
         $response = $client->account->balance();
         $this->assertObjectHasAttribute('balance', $response);
     }
+
+    public function testBaseUrl()
+    {
+        $subDomain = (string) bin2hex(random_bytes(10));
+        putenv('GREENSMS_BASE_URL=https://'. $subDomain .'.greensms.io:');
+        $client = $this->utility->getInstance();
+        $response = $client->account->balance();
+        putenv('GREENSMS_BASE_URL');
+
+        $this->assertInstanceOf(RestException::class, $response);
+        $this->assertStringContainsString($subDomain, $response->getMessage());
+    }
 }