diff --git a/openbsc/include/openbsc/gb_proxy.h b/openbsc/include/openbsc/gb_proxy.h
index 5c31321..0bda003 100644
--- a/openbsc/include/openbsc/gb_proxy.h
+++ b/openbsc/include/openbsc/gb_proxy.h
@@ -82,7 +82,10 @@
 	enum gbproxy_patch_mode patch_mode;
 	int tlli_max_age;
 	int tlli_max_len;
+
+	/* Experimental config */
 	int patch_ptmsi;
+	int acquire_imsi;
 
 	/* IMSI checking/matching */
 	int check_imsi;
@@ -143,6 +146,8 @@
 	uint8_t *mi_data;
 	size_t mi_data_len;
 
+	int imsi_acq_pending;
+	struct llist_head stored_msgs;
 
 	int enable_patching;
 };