Telephone call scheduled ahead of interview

[ItsAllFun]

Apologies for vague subject title but I haven't come across this before.
I applied for a job recently and have received an appointment for interview. The HR lady has also scheduled in a half hour phone-call prior to the interview.
The job application was direct to the company, so is it in the absence of a recruitment agent that they deem this necessary?
What should I expect on the phonecall? I don't want to exhaust all my questions with HR lady unless I am expected to?

I would treat it as a phone interview

It will be to check that you understand the role, salary, hrs etc they also might ask some short interview type questions.

We do it to try to reduce pointless interviews after doing a few where we wasted an good hour only to find out the candidate couldn't commit to the hours needed or would only accept a salary twice what was stated in the advert.

If the role is a good match according to the advert it should be a short simple call.

Cool, thanks.