diff --git a/ngcp/utils.lua b/ngcp/utils.lua
index 1ffcb08..454f1b3 100644
--- a/ngcp/utils.lua
+++ b/ngcp/utils.lua
@@ -31,6 +31,13 @@ function table.contains(table, element)
     return false
 end
 
+-- add if element is not in table
+function table.add(t, element)
+  if not table.contains(t, element) then
+    table.insert(t, element)
+  end
+end
+
 function table.val_to_str ( v )
   if "string" == type( v ) then
     v = string.gsub( v, "\n", "\\n" )
diff --git a/tests/utils.lua b/tests/utils.lua
index e269abb..2c10c71 100644
--- a/tests/utils.lua
+++ b/tests/utils.lua
@@ -31,6 +31,16 @@ TestUtils = {} --class
         assertError(table.contains, "hola",1)
     end
 
+    function TestUtils:test_table_add()
+        assertEquals(self.simple_list, {1,2,3})
+        table.add(self.simple_list, 1)
+        assertEquals(self.simple_list, {1,2,3})
+        table.add(self.simple_list, 5)
+        assertEquals(self.simple_list, {1,2,3,5})
+        table.add(self.simple_list, 4)
+        assertEquals(self.simple_list, {1,2,3,5,4})
+    end
+
     function TestUtils:test_table_tostring()
         assertError(table.tostring,nil)
         assertEquals(table.tostring(self.simple_list), "{1,2,3}")