Before you apply, try to learn the job name they are looking to fill. It will show that you took some interest and make you sound much better than trying to ask about the vacant job without a name. Wait a minute! Do companies have listings like this? Yes, sometimes they do, and the company may assume the job is obvious, but it would still have a correct name.
Vocabulary is always essential. A job may be called one name in one industry and another in a different sector even though it could be the same.
Another critical point is that you need to know the job name and description. Which departments does that job work with, and what does the company itself do. Researching before you make your first call or even try to use the right words on your application is essential.