Sponsoring organisations often require that you ‘alert’ an artificial call so that your opponents become aware that it is not natural. Various ways of alerting are in use but a common one is for the partner of the player making the artificial call to tap on the table. If you are using bidding boxes, you alert by showing the alert card. Here is an example:
If East’s 3♥ is a transfer, showing spades (or has any meaning other than a natural heart suit), West should alert immediately after the bid (ie before South has had the chance to call). West should explain the meaning of the 3♥ bid only in reply to an enquiry by one of the opponents.