VOIP Cloud Based Support Software

Good day.

I have a friend who wants to start a business that offer paid telephonic support.

How it needs to work is that someone must book a time slot, enter their credit card details or do some sort of payment, and then be allowed to talk to the operator for x amount of time.

Does such software exist?

If preferably it could be cloud based that wiuld be awesome.

Looking specifically for ready made solutions.

Regards.