[time-nuts] Time in Phone System

[Chris Albertson]

The data is formatted by the switch that connected the call.  This could be
a PBX that lives inside some small company or even in someone's house.
Today these switches are computers and they would use the system time.   So
the time you are getting is just whatever time the caller's equipment
thinks it is.  But today I'd bet every phone switch is on the Internet and
uses NTP to get the time.

I had a PBX setup at home for a while.  It is easy to do with open source
software.  Actually used an old modern card for signaling.   I got rid of
the system when it became to much trouble to maintain but now I get so many
"junk" calls I'm thinking about setting it back up and having it
automatically screen my calls.     When I had it running I could load
ANYTHING I wanted in the outgoing caller ID messages. The public phone
system completely accepts whatever you put in there.
Info here: trixbox <http://www.voip-info.org/wiki/view/trixbox>



On Mon, Jul 21, 2014 at 9:40 PM, Mark Sims <holrum at hotmail.com> wrote:

> Yes,  the caller ID data has time in it.   There are chips out there that
> decode caller ID.  I  signaling format isially is the old Bell 202 modem
> protocol.  The caller ID devices sort of half way answer the phone line
> when it detects the incoming call and the caller ID info is sent after the
> first ring.
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-- 

Chris Albertson
Redondo Beach, California