diff --git a/src/osmo-msc/msc_main.c b/src/osmo-msc/msc_main.c
index cffdaefc3..dc6b684fc 100644
--- a/src/osmo-msc/msc_main.c
+++ b/src/osmo-msc/msc_main.c
@@ -220,9 +220,11 @@ struct gsm_network *msc_network_alloc(void *ctx,
 	net->gsup_server_port = MSC_HLR_REMOTE_PORT_DEFAULT;
 
 	mgcp_client_conf_init(&net->mgw.conf);
-	net->mgw.tdefs = g_mgw_tdefs;
 	net->call_waiting = true;
 
+	net->mgw.tdefs = g_mgw_tdefs;
+	osmo_tdefs_reset(net->mgw.tdefs);
+
 	return net;
 }