> Well, I've seen where normal caller ID is wrong. It happens when someone
> dials in from a PBX, as in a hotel or office complex. When I call home
> from the local college, it shows some random trunk line phone number.
> That's probably what's happening to you.
It isn't really wrong in such cases. The number displayed is the one on
which the call originated. It may not be a number that correlates to the
extension behind the PBX, but it is indeed an outbound trunk on it.
Typically, a PBX will have direct-in trunks, where the last few digits
of the phone number don't correspond to a given physical trunk. When
you call someone on one of these "direct lines", your call goes over
a random trunk in the pool to the PBX, which then extracts the called
number (by any of a number of means, D-channel PRI signalling, DTMF,
etc.) and rings the extension mapped to these last digits.
For outbound calls, the PBX just grabs a random outbound trunk that
has no one-to-one correspondence to the extension. In some cases, it
may not even be a dialable number, but a "fictitious" number like
181-0987 or the like which will show up as "out of area" or "unavailable".
This can be trouble with calls to 9-1-1 where a PBX covers a wide area,
especially if it has a VoIP connection to a remote office several hundred
miles away.
99 times out of 100, an "out of area" on caller-ID is a telemarketer.
-- -- Jay Hennigan jay@west.net 805-884-6323 -- WestNet: Internet service to Santa Barbara, Ventura and the world.
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