The Presto setup wizard asks you to choose three call-in times during signup. But, if you log into the account manager web site after signup ( http://www.presto.com/signup ) and choose "Printing Mailbox Settings", you will be presented with the option for choosing 5 dial-in times.

I actually don't know why the system works this way, but it was probably designed this way to make the initial sign-up process quicker.

So, the answer is FIVE

Presto Insider: Peter Radsliff
VP Marketing, Presto Services Inc.