diff --git a/classes/Request.php b/classes/Request.php
index b4509db..03974d5 100644
--- a/classes/Request.php
+++ b/classes/Request.php
@@ -56,6 +56,10 @@ public function send()
             $arrParams['udh'] = $this->strUdh;
         }
 
+        if ($this->intCategory) {
+            $arrParams['smscat'] = $this->intCategory;
+        }
+
         $this->objLogger->addDebug('Sending the following to txtNation:', $arrParams);
 
         $objClient = new Client([
diff --git a/classes/SMSMessage.php b/classes/SMSMessage.php
index a60f5df..edc9ef8 100644
--- a/classes/SMSMessage.php
+++ b/classes/SMSMessage.php
@@ -25,6 +25,7 @@ class SMSMessage extends Request
     protected $fltValue = null;
     protected $strCurrency = null;
     protected $intReply = null;
+    protected $intCategory = null;
     protected $strEncoding = null;
     protected $blBinary = null;
     protected $strUdh = null;
@@ -200,6 +201,21 @@ public function binary($blBinary)
         return $this;
     }
 
+    public function category($intCategory)
+    {
+        if (!(Validator::numeric()->notEmpty()->length(3, 3)->validate($intCategory))) {
+            $this->objLogger->addError('Category must be a numeric string with a length of 3.');
+
+            throw new SMSMessageException('Category must be a numeric string with a length of 3.');
+        }
+
+        $this->intCategory = $intCategory;
+
+        $this->objLogger->addDebug('Category has been set to ' . $intCategory);
+
+        return $this;
+    }
+
     protected function validate()
     {
         $this->objLogger->addDebug('Validating the request');