NonprayingMantis: But why can?t Telecom charge less since the money is just an internal trade for them? Answer: Commerce commission would probably come down on the practice as anticompetitive. If Cook Islands charges other carriers like Voda and 2Degrees $15/MB for roaming but Telecom only charges, say, 50c/MB to it?s customers then this is anticompetitve because 2D and Voda cannot possibly compete with that price.
It really is just rorting - I can accept that some of the demand is seasonal in the CI so roaming should naturally be higher to maintain capacity - but really they should be charging absolutely everyone roaming $5mb max.
The markup on the Telecom NZ end is just rorting as well, for what is essentially just billing only - no capacity required.
Also here's a plug for TravelSim - http://www.travelsim.co.nz/