How reliable is incoming phone service in Southern Caribbean (Victory)

[cjhbeh]

We are getting ready to cruise soon :) but we are expecting a very important call from our newly departed college son that will come while we are at sea (he is only allowed to call us at a certain time/certain day/ for a few minutes- service academy) . We have never tried to or wanted to receive a phone call while on a cruise but this one we can't miss. Anyone have any experience with incoming calls either on the cruise ships or via Verizon? I know it will be expensive - but my real concern is whether the call will make it through to us... How reliable are the ship phones vs Verizon? Thanks in advance!!