Yes you could make somekind of solution for that.
To give you a idea:
Create a "User defined variable" called "NbrOfPrticipants" or whatever you like
Give it a value of 0
ceate a module called "CNFMeetMe100"
create a call flow in it for passcode check or whatever you need but just before the transfer into the conference add a Generic action were you increase the value of "NbrOfPrticipants" with one, add anothe generic module and play three announcements, the first you will have to record yourself "You are participant number " then add a announcement with "$NbrOfPrticipants.wav" and record a thirth one "in this conference"
As the VM Pro cannot see any participants leaving the conference this counter will not decrease automaiticly and you'll have to make a module to reset the value of "NbrOfPrticipants" after the conference has ended.
Be a Hero and figure it out, the help is awesome so use it.
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