On Wed, 10 Aug 1994, Dave Emery wrote:
My understanding of both IRIDIUM and the Loral effort are that the satellite will be used to directly connect a remote user to a ground based MTSO (switch) which will actually route the call out over land lines or another satellite link. This implies that the satellite is not being used as a classical bent-pipe repeater linking the transmitter of one satellite phone to the receiver of another, but rather as a space born cell-site linked to the MTSO via a separate radio system on a completely different frequency band not unlike the terrestrial microwave links that link most cell sites to the current MTSOs.
This means that there is no way for a mobile satellite user to bypass the switch and use the satellite directly to relay his communications to another satellite phone, just as there is no way in the current analog AMPS/NAMPS cellphone system for a user on one cellphone to talk directly to another cellphone without going through a cell site relay and the MTSO switch. Thus the switch can always serve as a gateway authenticating users, and providing billing and access control services. Dave Emery
Your understanding of how IRIDIUM(r) will work is incorrect. It most certainly WILL be the NORMAL operating mode for a subscriber unit (cell phone, if you will) to talk to another subscriber unit by only going through satellite links. The caller will be authenticated via a "home" equivalent to the MTSO switch, but the call itself will NOT go through the switch (or any other) unless it is to a phone number which is not a subscriber unit. ONLY in that case will the call be routed through the MTSO equivalent. Your thoughts about caller authentication are correct. I don't know if IRIDIUM is planning to do this correctly or not. Lyman Finger lrh@crl.com for PGP 2.7 Public Key Block.