This means that GMPCS phones will have terrestrial and satellite components, for example Iridium/GSM or even Iridium/GSM/AMPS.

However because of the extremities of the frequencies, CDMA and TDMA protocols, and the engineering needed to shield multiple modes, the first multi-mode phones will probably only be dual.

Odyssey, Globalstar and Iridium have already produced some dual-mode prototypes that will allow users to use the cheaper GSM mode when they are in a GSM coverage area, and then hand-over automatically to GMPCS satellite mode the moment they lose GSM coverage - without dropping the call.

Iridium's phones are made by Kyocera  & Motorola.

The Kyocera phone combo consistes of a smallesih terrestrial phone about the size of the Nokia 3110 that then fits  into an Iridium cradle for satellite coverage. The Motorola phone is shown on the right. It is a true dual-band phone.

While the GSM component will allow the user to roam normally on other GSM cellular networks, it’s highly unlikely that multi-mode phones will also encompass satellite network roaming.

This means that phones manufactured for use on one GMPCS system will probably be useable only on that satellite system, although users will be able to choose at the outset which cellular system - for example, either GSM or AMPS - they want as their phone’s alternative (terrestrial) mode.