captainvi...@gmail.com writes:
>I have this old Western Electric Comkey 416 (circa 1976) analog key telepho=
>ne system in my house. With two primary sets and the remainder being slaves=
> the system can handle 4 lines and 16 extensions. The sets all connect onto=
> 66 blocks with 25 pair cable. Yes it's antiquated but it does music on hol=
>d and intercom and serves our needs.= 20
>Lately I have noticed something peculiar. If I'm speaking with another part=
>y and I put them on hold the system will stay on hold indefinitely. However=
> if I put them on hold and they eventually hang up my system will eventuall=
>y go back on hook by itself. How can it do this? As far as I know this is j=
>ust a "dumb system. How could it know that the other party hung up and then=
> to release the line. I seriously doubt that they had the technology to do =
>this in 1975. Maybe someone (like an Ex telephone guy) might know if Wester=
>n Electric could have built anything that sophisticated into this system in=
> 1975 to detect anything like a kiss off, (I'm guessing) from the CO. Thank=
>s, Lenny
An abandoned call...
When the far end abandons the call, that CO tells your local CO.
It in turns drops [not reverses] the DC loop current for [ISTM]
450 ms. That was sufficient to drop the HOLD relay on a 1A2 KSU
with 400D cards.
This caused grief later when Caller-ID arrived. On a 1AESS,
it would announce such with a short DC glitch as it disabled
incoming audio, poked in a BEEEEEP, and reconnected the
audio. While the drop was far shorter, some cards would
drop off hold. Newer 400G & 400H cards would not.
--
A host is a host from coast to
coast.................wb8foz@nrk.com
& no one will talk to a host that's close..........................
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433