Answer: follow up call
Explanation:
From the question, we are informed that a representative from AT&T called Dr. Michaels after he switched to its new U-verse telephone system and that the firm wanted to make certain he was satisfied and asked if he had any questions concerning his new service.
The above is a follow up call. A follow up call is a call that is made after a transaction has taken place or previous enquiry regarding a product has been made in order to know the latest about the product.