Final answer:
When you need to answer the phone while talking to a customer, it is best to excuse yourself, answer the phone, and ask if you can call the customer back.
Step-by-step explanation:
When you need to answer the phone while talking to a customer, the appropriate action to take is to excuse yourself, answer the phone, and ask if you can call the customer back. This shows respect for both the customer and the person on the phone, acknowledging their importance. Putting the customer on hold or hanging up on them would not demonstrate good customer service or professionalism.