diff --git a/mbuni/mmsc/mms_billing.c b/mbuni/mmsc/mms_billing.c
index b8d23ed..78c74c9 100644
--- a/mbuni/mmsc/mms_billing.c
+++ b/mbuni/mmsc/mms_billing.c
@@ -33,7 +33,7 @@ static int mms_billingmodule_fini(void *module_data)
      return module_data ? fclose(module_data) : -1;
 }
 
-static double mms_billmsg(Octstr *from, List *to, unsigned long msg_size, Octstr *vaspid, void *module_data)
+static int mms_billmsg(Octstr *from, List *to, unsigned long msg_size, Octstr *vaspid, void *module_data)
 {
      return 0;
 }
diff --git a/mbuni/mmsc/mms_billing.h b/mbuni/mmsc/mms_billing.h
index 5b795b9..af13a16 100644
--- a/mbuni/mmsc/mms_billing.h
+++ b/mbuni/mmsc/mms_billing.h
@@ -47,7 +47,7 @@ typedef struct MmsBillingFuncStruct {
 /* Bills a message. Returns >= 0 if billed ok, -1 if message should be rejected, 
  * -2 on internal (temporary) error.
  */
-      double (*mms_billmsg)(Octstr *from, List *to, unsigned long msg_size, Octstr *vaspid, void *module_data);
+      int (*mms_billmsg)(Octstr *from, List *to, unsigned long msg_size, Octstr *vaspid, void *module_data);
      
       int (*mms_billingmodule_fini)(void *module_data);
 } MmsBillingFuncStruct;
diff --git a/mbuni/mmsc/mms_billing_shell.c b/mbuni/mmsc/mms_billing_shell.c
index bc43b10..8d8e05d 100644
--- a/mbuni/mmsc/mms_billing_shell.c
+++ b/mbuni/mmsc/mms_billing_shell.c
@@ -33,7 +33,7 @@ static int mms_billingmodule_fini(void *module_data)
      return 0;
 }
 
-static double mms_billmsg(Octstr *from, List *to, unsigned long msg_size, Octstr *vaspid, void *module_data)
+static int mms_billmsg(Octstr *from, List *to, unsigned long msg_size, Octstr *vaspid, void *module_data)
 {
      int i;
 
@@ -43,8 +43,12 @@ static double mms_billmsg(Octstr *from, List *to, unsigned long msg_size, Octstr
 	  Octstr *s;
 	  s = octstr_format("%s '%s' '%s'", octstr_get_cstr(script), octstr_get_cstr(from), octstr_get_cstr(list_get(to, i))); 
 	  if (s) {
-	       system(octstr_get_cstr(s));	  
+	       int ret = system(octstr_get_cstr(s));	  
 	       octstr_destroy(s);
+	       if (ret < 0)
+		    return -2;
+	       else if (WEXITSTATUS(ret) != 0)
+		    return -1;
 	  }
      }
      return 0;