Satellite communication is a technique which has been used in telemedicine,
often for educational purposes. Almost all of the work has concerned the u
se of fixed satellite terminals. Mobile satellite services (MSS) provide tw
o-way voice and data communication from hand-held terminals, where the fina
l link to the subscriber is by satellite. A number of new MSS systems are e
xpected to become operational by 2001, providing either regional or global
coverage. The most well developed proposals are Globalstar, ICO, Iridium an
d Odyssey. All the proposed systems use non-geostationary satellites. The M
SS systems will allow international travellers to make and receive calls us
ing a unique telephone number for their handset anywhere in the world where
the service has been authorized by the local regulatory authorities. Data
and fax services will also be available. By 2002 the proposed MSS systems m
ight serve a million subscribers in Western Europe, although this is less t
han 1% of the expected number of mobile phone users. To recoup the developm
ent costs, the price of MSS airtime is expected to be high compared with ex
isting mobile phones.