Untrue information in sales

After graduation, Becky worked in a company that distributed electronic appliances.  When customers phoned the office asking for information on certain electrical appliances, Becky would look up the model, the price, and the inventory level in the computer database.  The boss always instructed Becky to tell the customers that they had the goods in stock, even if it wasn’t true. The boss explained that this tactic was to secure the orders first even when the required model was certainly out of stock in the market.  He argued that, as long as the customers did not know the stock situation, it was no harm for customers to wait and new models could even be suggested while they were waiting.  This stalling tactic was better than letting customers go to the competitors.  The boss’ argument sounded justified, but Becky did not feel comfortable because this meant she had to lie frequently.

What should Becky do?  Would she lose her sense of integrity?  Should she try to win customers in another way?