Index: funcs/func_devstate.c
===================================================================
--- funcs/func_devstate.c	(revision 209992)
+++ funcs/func_devstate.c	(working copy)
@@ -39,6 +39,7 @@
 #include "asterisk/pbx.h"
 #include "asterisk/utils.h"
 #include "asterisk/linkedlists.h"
+#include "asterisk/event.h"
 #include "asterisk/devicestate.h"
 #include "asterisk/cli.h"
 #include "asterisk/astdb.h"
@@ -96,6 +97,7 @@
 
 
 static const char astdb_family[] = "CustomDevstate";
+static struct ast_event_sub *custom_devstate_subscription;
 
 static int devstate_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
 {
@@ -188,6 +190,19 @@
 	return ast_devstate_val(buf);
 }
 
+static void custom_devstate_sub_callback(const struct ast_event *ast_event, void *data)
+{
+	const char *device = ast_event_get_ie_str(ast_event, AST_EVENT_IE_DEVICE);
+
+	if(!strncmp(device, "Custom:", 7)) {
+		
+		const char *dev_state = ast_devstate_str(ast_event_get_ie_uint(ast_event,
+				AST_EVENT_IE_STATE));
+		const char *dev_name = strrchr(device, ':') + 1;
+		ast_db_put(astdb_family, dev_name, dev_state);
+	}
+}
+
 static char *handle_cli_devstate_list(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
 {
 	struct ast_db_entry *db_entry, *db_tree;
@@ -315,6 +330,10 @@
 {
 	int res = 0;
 
+	if (custom_devstate_subscription) {
+		ast_event_unsubscribe(custom_devstate_subscription);
+	}
+
 	res |= ast_custom_function_unregister(&devstate_function);
 	res |= ast_custom_function_unregister(&hint_function);
 	res |= ast_devstate_prov_del("Custom");
@@ -340,7 +359,10 @@
 	}
 	ast_db_freetree(db_tree);
 	db_tree = NULL;
-
+	custom_devstate_subscription = ast_event_subscribe(AST_EVENT_DEVICE_STATE_CHANGE,
+		custom_devstate_sub_callback, "custom_devstate_subscription", NULL,
+		AST_EVENT_IE_END);
+	
 	res |= ast_custom_function_register(&devstate_function);
 	res |= ast_custom_function_register(&hint_function);
 	res |= ast_devstate_prov_add("Custom", custom_devstate_callback);