It's unlikely you'll be able to make usable wifi calls or facetime on the ship. The ship's wifi is painfully slow (speeds barely abode dialup). It uses an older technology of satellite internet which has very limited bandwidth, slow speeds and extremely long lag (don't bother paying for "premium" internet, it's not really faster).
The ship also has a proper cell tower which uses "satellite phone at sea" service which is usable, but is extremely expensive (around $5 a minute and insane data rates) and is not included in 99% of mobile phone plans.