I talked to the Millionaire staff at an audition,
and they said that now, once you get all 5 right
during the 5 day period the phonelines are open, that
that is the only time you can qualify during that 5
day period. After that, you may be drawn out at
random to be in the phone player pool (answering all 5
does not guarantee you will be in the pool, and there
is no way to know if you have been selected). You
will not need to call in again until they begin a new
phone game period. Unfortunately, they said not to get
your hopes up, because the number of people who get
all 5 correct once during the period is staggering.
Hope this helps.