diff --git a/openbsc/include/openbsc/ipaccess.h b/openbsc/include/openbsc/ipaccess.h
index 135fce2..00642ff 100644
--- a/openbsc/include/openbsc/ipaccess.h
+++ b/openbsc/include/openbsc/ipaccess.h
@@ -31,6 +31,10 @@
 	IPAC_PROTO_MGCP_OLD	= 0xfc,
 };
 
+enum ipaccess_proto_ext {
+	IPAC_PROTO_EXT_CTRL	= 0x00,
+};
+
 enum ipaccess_msgtype {
 	IPAC_MSGT_PING		= 0x00,
 	IPAC_MSGT_PONG		= 0x01,
@@ -70,6 +74,7 @@
 int ipaccess_rcvmsg_base(struct msgb *msg, struct bsc_fd *bfd);
 struct msgb *ipaccess_read_msg(struct bsc_fd *bfd, int *error);
 void ipaccess_prepend_header(struct msgb *msg, int proto);
+void ipaccess_prepend_header_ext(struct msgb *msg, int proto);
 int ipaccess_send_pong(int fd);
 int ipaccess_send_id_ack(int fd);
 int ipaccess_send_id_req(int fd);
diff --git a/openbsc/src/libabis/input/ipaccess.c b/openbsc/src/libabis/input/ipaccess.c
index ecf7038..e1e314b 100644
--- a/openbsc/src/libabis/input/ipaccess.c
+++ b/openbsc/src/libabis/input/ipaccess.c
@@ -551,6 +551,15 @@
 	return ret;
 }
 
+void ipaccess_prepend_header_ext(struct msgb *msg, int proto)
+{
+	struct ipaccess_head_ext *hh_ext;
+
+	/* prepend the osmo ip.access header extension */
+	hh_ext = (struct ipaccess_head_ext *) msgb_push(msg, sizeof(*hh_ext));
+	hh_ext->proto = proto;
+}
+
 void ipaccess_prepend_header(struct msgb *msg, int proto)
 {
 	struct ipaccess_head *hh;