There are multiple free online conference call systems available.
From our experience, https://www.freeconferencecall.com/ is the best. They have the option of saving all recordings for future listening over the phone.
For phone instructions, you can click on this link. https://www.freeconferencecall.com/host-instructions#phone-keypad-commands
The best is to open one account for each melamed so they can host their meetings at the same time.
The number provided is from a 605 area code. So for people that still pay long-distance, it might be expensive. You can maybe combine it with a local number that gets forwarded to that number through your phone provider.