Motorola Direct Talk
From The RadioReference Wiki
The OFF Network (DirecTalk) uses a FHSS system that uses a format of channels and codes with in the channels for pattern sequence. They put out about 1/2 watt and feature either a group call format (meaning everyone one on Ch 1 code 1) or a private call format (using your PTN based on SIM card). Range will vary with terrain, reports have been of one to three miles.
No activation is required, although a Sim card of Nextel or Boost Mobile is required to get to the screen to go to Direct Talk. These cards are cheap on ebay.
Q:Can you power them up and place them into DirecTalk mode w/o a SIM card in place.
I am not sure if you have any SIM cards or maybe they did come with the phones. BUt, I have heard some people say that w/o a SIM card you really can not get past the please insert SIM screen.
Using them on a cruise ship in international waters.
I have heard this asked by many people and I do not recall one set answer. I do want to say this: while they are in the ISM band for operation, based on the United States FCC frequency assignment sometimes it is different in international waters.
Most Motorola Iden phones from Nextel or Boost will have this function available.
The favorite and cheapest so far is the i355.