diff --git a/library/S1AP_CodecPort.ttcn b/library/S1AP_CodecPort.ttcn
new file mode 100644
index 0000000..59cef18
--- /dev/null
+++ b/library/S1AP_CodecPort.ttcn
@@ -0,0 +1,82 @@
+module S1AP_CodecPort {
+
+/* Simple S1AP Codec Port, translating between raw SCTP primitives with
+ * octetstring payload towards the IPL4asp provider, and S1AP primitives
+ * which carry the decoded S1AP data types as payload.
+ *
+ * (C) 2019 by Harald Welte <laforge@gnumonks.org>
+ * All rights reserved.
+ *
+ * Released under the terms of GNU General Public License, Version 2 or
+ * (at your option) any later version.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+	import from IPL4asp_PortType all;
+	import from IPL4asp_Types all;
+	import from S1AP_PDU_Descriptions all;
+	import from S1AP_Types all;
+
+	type record S1AP_RecvFrom {
+		ConnectionId	connId,
+		HostName	remName,
+		PortNumber	remPort,
+		HostName	locName,
+		PortNumber	locPort,
+		S1AP_PDU	msg
+	};
+
+	template S1AP_RecvFrom t_S1AP_RecvFrom(template S1AP_PDU msg) := {
+		connId := ?,
+		remName := ?,
+		remPort := ?,
+		locName := ?,
+		locPort := ?,
+		msg := msg
+	}
+
+	type record S1AP_Send {
+		ConnectionId	connId,
+		S1AP_PDU	msg
+	}
+
+	template S1AP_Send t_S1AP_Send(template ConnectionId connId, template S1AP_PDU msg) := {
+		connId := connId,
+		msg := msg
+	}
+
+	private function IPL4_to_S1AP_RecvFrom(in ASP_RecvFrom pin, out S1AP_RecvFrom pout) {
+		pout.connId := pin.connId;
+		pout.remName := pin.remName;
+		pout.remPort := pin.remPort;
+		pout.locName := pin.locName;
+		pout.locPort := pin.locPort;
+		pout.msg := dec_S1AP_PDU(pin.msg);
+	} with { extension "prototype(fast)" };
+
+	private function S1AP_to_IPL4_Send(in S1AP_Send pin, out ASP_Send pout) {
+		pout.connId := pin.connId;
+		pout.proto := {
+			sctp := {
+				sinfo_stream := omit,
+				sinfo_ppid := 18,
+				remSocks := omit,
+				assocId := omit
+			}
+		};
+		pout.msg := enc_S1AP_PDU(pin.msg);
+	} with { extension "prototype(fast)" };
+
+	type port S1AP_CODEC_PT message {
+		out	S1AP_Send;
+		in	S1AP_RecvFrom,
+			ASP_ConnId_ReadyToRelease,
+			ASP_Event;
+	} with { extension "user IPL4asp_PT
+		out(S1AP_Send -> ASP_Send:function(S1AP_to_IPL4_Send))
+		in(ASP_RecvFrom -> S1AP_RecvFrom: function(IPL4_to_S1AP_RecvFrom);
+		   ASP_ConnId_ReadyToRelease -> ASP_ConnId_ReadyToRelease: simple;
+		   ASP_Event -> ASP_Event: simple)"
+	}
+}