diff --git a/include/osmocom/msc/sgs_server.h b/include/osmocom/msc/sgs_server.h
new file mode 100644
index 0000000..a89022d
--- /dev/null
+++ b/include/osmocom/msc/sgs_server.h
@@ -0,0 +1,53 @@
+/* (C) 2018-2019 by sysmocom s.f.m.c. GmbH
+ * All Rights Reserved
+ *
+ * Author: Harald Welte, Philipp Maier
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <arpa/inet.h>
+#include <osmocom/gsm/protocol/gsm_29_118.h>
+
+#define DEFAULT_SGS_SERVER_IP "0.0.0.0"
+#define DEFAULT_SGS_SERVER_VLR_NAME "vlr.example.net"
+
+/* global SGs state */
+struct sgs_state {
+	/* list of MMEs (sgs_mme_ctx) */
+	struct llist_head mme_list;
+
+	/* list of SCTP client connections */
+	struct llist_head conn_list;
+
+	/* SCTP server for inbound SGs connections */
+	struct osmo_stream_srv_link *srv_link;
+
+	struct {
+		char local_addr[INET6_ADDRSTRLEN];
+		uint16_t local_port;
+		/* user-configured VLR name (FQDN) */
+		char vlr_name[SGS_VLR_NAME_MAXLEN];
+		/* timers on VLR side */
+		unsigned int timer[_NUM_SGS_STATE_TIMERS];
+		/* countrs on VLR side */
+		unsigned int counter[_NUM_SGS_STATE_COUNTERS];
+	} cfg;
+};
+
+struct sgs_state *sgs_server_alloc(void *ctx);
+int sgs_server_open(struct sgs_state *sgs);