What can be concluded about the company after receiving many calls?

The conclusion that the company's advert was effective is supported by the context of receiving many calls. An increase in inquiries typically suggests that the advertisement successfully caught the attention of potential customers, prompting them to reach out for more information or to inquire about products or services. This correlation between calls and ad effectiveness indicates that the marketing strategy is resonating with the audience.

While it's possible that the company could have had other issues or challenges that led to an influx of calls, or that they may consider changing strategies based on the responses they receive, those interpretations are less direct and do not stem immediately from the mere fact of receiving many calls. Therefore, the most straightforward inference drawn from the situation is the effectiveness of the advertisement.