I had a similar experience, although I was lucky in that the recruiting manager just called without warning one afternoon, so I didn't have time to think about it. My experience is likely different, because I was looking at EMBAs and online MBAs, but that first call was really helpful both in giving me more confidence for future calls, but also to help me crystallize my thinking about what I was looking to get out of an MBA.

So if I were you I'd accept the invitation to talk, but be honest with the recruitment manager, saying that you are in the early stages of considering an MBA and don't have all the answers yet, but wanted to start with some basic research. I imagine you probably have some vague ideas about what you're looking to get out of an MBA (hopefully more than just an increase in salary) and there was something about the school that appealed to you enough to request a brochure, and you can schedule the Skype call a bit in the future to give you time to maybe do a little more research on the school in the meantime, so that you have more of your bases covered.

@TM1209 I guess there is no harm in talking to the recruitment manager. Just be honest. A MBA at the end of the day is just like any other produce/service (albeit an expensive one). The prompt email to talk to you probably just indicates the stiff competition for attracting talent & tuition amongst business schools (especially the also ran/second rung variety).

@mcgr @LostInTranslation
Thanks a lot for sharing your experience.
In the end, I chose to have a call with recruitment manager. The manager was quite friendly and even kindly understood that I was nervous.
It went well so far as I could find myself having to do more research on MBA.
Many thanks once again.