diff --git a/include/osmocom/mgcp/mgcp.h b/include/osmocom/mgcp/mgcp.h
index 8cdff59..27b1e35 100644
--- a/include/osmocom/mgcp/mgcp.h
+++ b/include/osmocom/mgcp/mgcp.h
@@ -261,7 +261,10 @@
 	uint32_t last_call_id;
 
 	/* trunk handling */
-	struct mgcp_trunk_config trunk;
+
+	/* virtual trunk for RTP - RTP endpoints */
+	struct mgcp_trunk_config *virt_trunk;
+	/* physical trunks with underlying E1 endpoints */
 	struct llist_head trunks;
 
 	enum mgcp_role role;