Re:The forgotten war on beepers
by karma_pharmer on Thursday April 18, 2024 @05:34AM
(#40074433)
Yes, Iridium SBD requires transmitting before you can receive.
I did not know about Global Data Burst; I think that's what you're referring to. Holy cow it's expensive though, although I guess it has to be since you're using a lot more bandwidth*footprint. Like $6.00 per message per delivery area expensive. And they're kinda vague on how big a "delivery area" is.
No, I’m referring to the Iridium pager, which is just its own service and has been around longer than SBD, I believe. Messages were (are?) free to send on top of a monthly flat subscription rate per pager.
GDB seems to be a successor to that, though.
GDB is just a branding for their own flavor of what they're selling which is Iridium Burst, which also appear to run on the 9602/9603 SBD modules, so... maybe Iridium Burst is just spicier Iridium SBD?
SBD is bidirectional unicast (and mandatorily so; as you say, SBD can't transmit to devices before they initiate a mailbox exchange, with the exception of a "message waiting" indicator.
Iridium Burst seems to be multicast-capable, and optionally bidirectional or unidirectional, so "spicier SBD" makes sense!
But their paging service was definitely unidirectional and unicast. Here's an old talk on decoding the signal, if you're curious: https://media.ccc.de/v/31c3_-_6236_-_en_-_saal_1_-_201412281...
You had to manually update your paging location by dialing some number or by using a web interface when moving significantly, or link an Iridium phone to your pager, which would then automatically update the paging area (MDA) every time you made a call.
What you mean is probably Iridium SBD, but that’s a different, bidirectional service (also used for pager-like devices these days).