Hi, John:
0) Allow me to share some old-fashioned telephony line-man tricks,
kind of trade-secretes. 😉
1) "Analog phones can not be detected unless they're off hook ... ":
This is true only if your measurement capability is limited within
the pure DC (Direct Current) domain. A tiny step outside of it will open
up some possibilities. As we all know, a POTS (Plain Old Telephone Set)
in OnHook state will ring when Ringing Signals are applied from the
serving telephone switch. This is because there is a Ringer Circuit
always connected across the Tip-Ring pair of the subscriber loop wire
pair. The basic component of a Ringer is an electro-mechanical device
that appears as an inductor (L) on the electrical side and functions as
a hammer on the mechanical side. To prevent the L from constantly
drawing 48VDC battery current, a series capacitor (C) has to be
included. Consequently, AC (Alternate Current) signals are used to
activate the Ringer. Depending on the country, this AC frequency is
around 16 - 20 Hz. So, the Ringer Circuit is designed as a series L-C
resonator that appears as a resistive load at that chosen frequency.
There is a range of L & C combination values that can be used for this
purpose. Practically, C comes out to be around 1uF (One Micro-Farad) and
rated at least 250VAC to survive the voltage swing of the Ringing
Signal. Accordingly, there are ways to detect a POTS by measuring its L
or C, but not by a pure DC approach.
2) " ... between sitting idle or the cables cut. ":
Inductance measurements are generally more involved. So, treating
an OnHook POTS as a capacitor is a simpler way for the current purpose.
There are a couple possible techniques. For example:
A. A line-man can put a voltmeter across a subscriber loop wire
pair to verify that it is being energized by the 48VDC battery from the
CO (Central Office), and is not shorted or leaking. Upon disconnecting
one wire of the pair from the CO side, if the voltmeter reading drops to
zero right away, the loop is an open loop (without a POTS). If its
reading maintains for awhile (actually, a fairly long time), there is at
least one POTS (1uF or equivalent) on the line.
B. A "Battery Reversal Tester" can be used in the CO to actually
measure how much charge is stored at the end of a subscriber loop, by
observing the length of time that a subscriber line voltage takes to
reverse upon flipping the polarity of the 48VDC battery voltage applied
to it. This is done through controlled known discharge circuit, based on
RC time-constant.
C. With a "calibrated" Battery Reversal Tester, the CO craftsman
can tell how many POTS are plugged into the jacks along a subscriber
loop. That is, the more POTS are plugged in, the longer it takes to
reverse the voltage on the subscriber side. This is where the REN
(Ringer Equivalent Number) on the POST label comes from. For example,
when a subscriber complains that ringing is too weak, the CO can tell
whether that subscriber has too many phones plugged in, even without a
physical visit. The convention established by FCC is 5 REN (or about
5uF) - Maximum number of ringers (POTS) for the subscriber and minimum
Ringing Signal capability for the CO.
D. A seasoned line-man can do Step C. on the pole by himself,
even without the support of the CO instrumentation, using everyday VOM
(Volt-Ohm-MiliAmper) meter which is in his basic tool kit.
Hope this helps.
Happy Holidays!
Abe (2024-12-15 23:55 EST)
On 2024-12-12 11:08, Josh Luthman wrote:
I understand it is frustrating. Analog phones can not be detected
unless they're off hook so I don't see how a provider can detect
between sitting idle or the cables cut.
How do you know for certain it is an outage in the area and not just
the customer(s) you've talked to?
There is a requirement for outages required by the FCC.
On Thu, Dec 12, 2024 at 10:53 AM John Neiberger <jneiber...@gmail.com>
wrote:
Understandable for a single customer. It sounds like this a huge part
of the town that has no phones, including the rural folks who live
outside of cell coverage, many of whom are elderly. I just found out
that they had indeed called CL to complain days ago and CL told them
they couldn't get out there to look at it until the 20th. These are
rural people with no backup to their landline who have been without
phone for days already and CL expects them to go another week or two?
Unbelievable. Also, when I called CL on their behalf, I was told they
had no record of an outage in the area.
Thankfully, I was able to reach someone at Lumen who was able to get
someone involved. There is supposed to be a tech there right now, but
he no-showed. I think an FCC complaint is in order.
On Thu, Dec 12, 2024 at 8:36 AM Josh Luthman
<j...@imaginenetworksllc.com> wrote:
>
> If it's landline copper phone, it's kind of hard for a provider
to see the lack of customers off hook. The electrical circuit
being open is expected until the customer picks up the load/off
hooks the phone.
>
> On Wed, Dec 11, 2024 at 11:54 PM John Neiberger
<jneiber...@gmail.com> wrote:
>>
>> Yep. I finally found some contacts at Lumen who ran it up the
chain. I
>> also did report it to the Colorado PUC. I'm still confused
about how
>> so many homes and businesses could be without service and
Centurylink
>> wouldn't know about it. It's a small town, and I'm starting to
think
>> everyone thought that the phone company must know about it because
>> there so many affected, so no one bothered to call them. I
don't know.
>> None of it makes any sense. But at least we have someone
scheduled to
>> drive over there tomorrow and check it out.
>>
>> John
>>
>> On Wed, Dec 11, 2024 at 9:08 PM Evan Moyer <evmo...@gmail.com>
wrote:
>> >
>> > Have you tried filing a complaint with your state's public
utility commission? POTS service is usually regulated by them.
>> >
>> > Just a thought
>> >
>> >
>> > On Wed, Dec 11, 2024, 7:52 PM John Neiberger
<jneiber...@gmail.com> wrote:
>> >>
>> >> I apologize for using NANOG for this, but I need to get some
traction
>> >> on a telephone outage affecting a large number of homes in a
small
>> >> town that Centurylink seems to be unaware of. The affected
customers
>> >> have had no phone service for days and none of them know
what's going
>> >> on. Centurylink customer service says there are no outages
in the area
>> >> and just want to dispatch a tech to an individual home
rather than
>> >> escalate this as the emergency that it is. This is a rural
area with
>> >> poor cell service, so many of these customers have no
alternative. I'm
>> >> particularly concerned that many of the affected customers
would be
>> >> unable to reach emergency services, and haven't been able to
for 3-4
>> >> days already.
>> >>
>> >> If someone has a contact at Centurylink that can escalate
this, please
>> >> contact me off-list.
>> >>
>> >> Many thanks!
>> >> John Neiberger
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