[GadgetKen]

Telna works on Digicel French Antilles in St. Maarten by callback. Callback is easier than other sims I've used that often required a USSD string. Had to file a trouble ticket since didn't work right away but worked today when did a manual carrier selection. Other French or Dutch carriers don't allow registration or only allow emergency calls.
Did try Skype over hotel wifi but Voip quality was pretty bad..best for email or light web browsing instead.
Also used Inmarsat prepaid from room balcony.
Hotel is lovely but room phone has a USD rate of $6 for the first minute and $4.50 for additional minutes. Telna at fifty cents a minute or Inmarsat at a little over a dollar are a better deal.