Conference Service

I need to count people entering a meetme conference.

I would like them to enter possibly a number such as when they call in and go to an IVR or script.

They would then hear please press the number that corresponds to the number of people listening to the conference at that location.

Then as long as they were in the conference when somebody calls in it could state as it does now a user count.

Such as calling into the conference and then using the menu pressing say the 4 key on the menu hear the current callers based on the number they pressed before they were sent into the conference.

Alternatively

Could a user be sent to an extension and leave a voice mail with the number of people they have that could be then listened to during the conference.

Ideas and I am a newbe