Resolved #50

src/Gateways/HuaxinGateway.php

@@ -45,7 +45,7 @@ class HuaxinGateway extends Gateway
             'account' => $config->get('account'),
             'password' => $config->get('password'),
             'mobile' => $to,
-            'content' => $message->getContent(),
+            'content' => $message->getContent($this),
             'sendTime' => '',
             'action' => 'send',
             'extno' => $config->get('ext_no'),

src/Gateways/LuosimaoGateway.php

@@ -44,7 +44,7 @@ class LuosimaoGateway extends Gateway
 
         $result = $this->post($endpoint, [
             'mobile' => $to,
-            'message' => $message->getContent(),
+            'message' => $message->getContent($this),
         ], [
             'Authorization' => 'Basic '.base64_encode('api:key-'.$config->get('api_key')),
         ]);

src/Gateways/YunpianGateway.php

@@ -45,7 +45,7 @@ class YunpianGateway extends Gateway
         $result = $this->post($endpoint, [
             'apikey' => $config->get('api_key'),
             'mobile' => $to,
-            'text' => $message->getContent(),
+            'text' => $message->getContent($this),
         ]);
 
         if ($result['code']) {