diff --git a/src/NB_SMS.cpp b/src/NB_SMS.cpp
index 85c391f..55b6709 100644
--- a/src/NB_SMS.cpp
+++ b/src/NB_SMS.cpp
@@ -436,13 +436,15 @@ void NB_SMS::flush()
   }
 }
 
-void NB_SMS::clear()
+void NB_SMS::clear(int flag)
 {
   _ptrUTF8 = "";
 
   while (MODEM.ready() == 0);
 
-  MODEM.sendf("AT+CMGD=0,2");
+  if (flag<1 || flag>4) flag = 2;
+
+  MODEM.sendf("AT+CMGD=0,%d",flag);
 
   if (_synch) {
     MODEM.waitForResponse(55000);
diff --git a/src/NB_SMS.h b/src/NB_SMS.h
index 26b85ae..c5b3777 100644
--- a/src/NB_SMS.h
+++ b/src/NB_SMS.h
@@ -22,6 +22,11 @@
 
 #include <Stream.h>
 
+#define NB_SMS_CLEAR_READ             (1)
+#define NB_SMS_CLEAR_READ_SENT        (2)
+#define NB_SMS_CLEAR_READ_SENT_UNSENT (3)
+#define NB_SMS_CLEAR_ALL              (4)
+
 class NB_SMS : public Stream {
 
 public:
@@ -86,7 +91,7 @@ class NB_SMS : public Stream {
   
   /** Delete all read and sent SMS from Modem memory and process answer
    */
-  void clear();
+  void clear(int flag = NB_SMS_CLEAR_READ_SENT);
 
 private:
   bool _synch;