diff --git a/library/GTPv1U_CodecPort_CtrlFunct.ttcn b/library/GTPv1U_CodecPort_CtrlFunct.ttcn
new file mode 100644
index 0000000..3a86fc9
--- /dev/null
+++ b/library/GTPv1U_CodecPort_CtrlFunct.ttcn
@@ -0,0 +1,13 @@
+module GTPv1U_CodecPort_CtrlFunct {
+
+  import from GTPv1U_CodecPort all;
+  import from IPL4asp_Types all;
+
+  external function f_GTPU_listen(
+    inout GTPU_PT portRef,
+    in HostName locName,
+    in PortNumber locPort,
+    in ProtoTuple proto,
+    in OptionList options := {}
+  ) return Result;
+}