diff --git a/include/openbsc/transaction.h b/include/openbsc/transaction.h
index 07ab7a7..713d878 100644
--- a/include/openbsc/transaction.h
+++ b/include/openbsc/transaction.h
@@ -9,6 +9,14 @@
 #include <osmocom/gsm/gsm0411_smc.h>
 #include <osmocom/gsm/gsm0411_smr.h>
 
+enum bridge_state {
+	BRIDGE_STATE_NONE,
+	BRIDGE_STATE_LOOPBACK_PENDING,
+	BRIDGE_STATE_LOOPBACK_ESTABLISHED,
+	BRIDGE_STATE_BRIDGE_PENDING,
+	BRIDGE_STATE_BRIDGE_ESTABLISHED,
+};
+
 /* One transaction */
 struct gsm_trans {
 	/* Entry in list of all transactions */
@@ -57,6 +65,11 @@
 			struct gsm_sms *sms;
 		} sms;
 	};
+
+	struct {
+		struct gsm_trans *peer;
+		enum bridge_state state;
+	} bridge;
 };
 
 
@@ -74,7 +87,7 @@
 
 int trans_assign_trans_id(struct gsm_network *net, struct vlr_subscr *vsub,
 			  uint8_t protocol, uint8_t ti_flag);
-int trans_has_conn(const struct gsm_subscriber_connection *conn);
+struct gsm_trans *trans_has_conn(const struct gsm_subscriber_connection *conn);
 void trans_conn_closed(struct gsm_subscriber_connection *conn);
 
 #endif