diff --git a/include/s11/s11.h b/include/s11/s11.h
new file mode 100644
index 0000000..cdc6536
--- /dev/null
+++ b/include/s11/s11.h
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2019, Infosys Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */  
+ 
+
+#ifndef __UE_S11_H_
+#define __UE_S11_H_
+
+#include <stdint.h>
+#include "log.h"
+#include "s11_structs.h"
+
+/*No of threads handling S11 GTPv2 messages coming in*/
+#define S11_THREADPOOL_SIZE 5
+
+#define S11_GTPV2C_BUF_LEN	4096
+
+/*GTPv2c message types*/
+#define S11_GTP_CREATE_SESSION_REQ	32
+#define S11_GTP_CREATE_SESSION_RESP	33
+#define S11_GTP_MODIFY_BEARER_RESP	35
+#define S11_GTP_DELETE_SESSION_RESP	37
+#define S11_GTP_RELEASE_BEARER_REQ	170
+#define S11_GTP_RELEASE_BEARER_RESP	171
+#define S11_GTP_DDN			176
+
+/*GTPv2c IE message types*/
+#define S11_IE_CAUSE		2
+#define S11_IE_FTEID_C		87
+#define S11_IE_PAA		79
+#define S11_IE_APN_RESTRICTION	127
+#define S11_IE_BEARER_CTX	93
+#define S11_IE_EPS_BEARER_ID	73
+
+int
+init_s11();
+
+void
+handle_s11_message(void *message);
+
+int
+init_s11();
+
+void
+handle_s11_message(void *message);
+
+int
+s11_transation(char * buf, unsigned int len);
+
+void* create_session_handler(void *);
+void* modify_bearer_handler(void *);
+void* release_bearer_handler(void *); 
+void* delete_session_handler(void *);
+void* ddn_ack_handler(void *);
+/*int s11_CS_resp_handler(char *message);
+int s11_MB_resp_handler(char *message);
+int s11_DS_resp_handler(char *message);
+int s11_RB_resp_handler(char *message);
+int s11_DDN_handler(char *message);
+*/
+
+
+void
+bswap8_array(uint8_t *src, uint8_t *dest, uint32_t len);
+
+int parse_gtpv2c_IEs(char *msg, int len, struct s11_proto_IE *proto_ies);
+
+#endif /*S11_H*/