add 'direction' chan var

src/switch_channel.c

@@ -241,6 +241,7 @@ SWITCH_DECLARE(switch_status_t) switch_channel_alloc(switch_channel_t **channel,
 	(*channel)->hangup_cause = SWITCH_CAUSE_NONE;
 	(*channel)->name = "";
 	(*channel)->direction = direction;
+	switch_channel_set_variable(*channel, "direction", switch_channel_direction(*channel) == SWITCH_CALL_DIRECTION_OUTBOUND ? "outbound" : "inbound");
 
 	return SWITCH_STATUS_SUCCESS;
 }