asterisk users - Jun 2003 - Question :: groundstart and loopstart

Hello Astrites,

I was just about to send out a long email about not being able to detect hang-up
with my CAC II FXO module on my PSTN POTS lines.  I had tried many
configurations.  I had attached a toner to the line to see if I was getting this
"disconnect supervision" signal after hang-up.  (toner has a line
powered light in the off position)  It seemed that I was getting the signal, as:

    The light was steady on onhook
    When the line rang the light dimmed.
    When I picked up the line stayed dim (If I remember correctly)
    When the other end hung up the light stayed on
    Then turned off momentarily a few seconds later.  (I suspected this was
"disconnect supervision")

Anyway asterisk never detected hang-up.  Everything else worked.  I was
frustrated as hell.

After a few days of trying everything, I tried to set my CAC II FXO module to
Groundstart and configured zaptel.conf and zapata.conf to groundstart signaling.

Voila!  Everything work!

The question is how does groundstart and loopstart work?  How was I able to have
a somewhat working system using loopstart when it seems that the phone company
signaling was groundstart?  Can I assume that my lines are indeed groundstart?

I am really happy that it works.  I can now begin the process of deployment with
a much greater feeling of security.

Jason

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On 2003-06-17 at 16:05, Surfer Dude (swell@labranch.com) wrote:
>    Can I assume that my lines are indeed groundstart?
If you pick up your line on a normal phone and hear dialtone, then you
have loop start.  If you had ground start, you would need to ground one
side of the line to get dialtone.

The nice thing about ground start is that it gives you guaranteed
disconnect supervision.  It seems your channel bank may think that loop
start lines do not give CPC (disconnect supervision) and so it isn't
looking for it.

Whenever possible, it is better to use ground start lines.  However,
most FXO cards will not support ground start origination.  Calls
terminating on ground start lines usually provide ring voltage as well
as the ground signal, though I have seen some braindead equipment that
does not send ring voltage for ground start lines.

As far as I have been told, ground start does not exist outside North
America.  I would love to be proven wrong on this because getting good
disconnect supervision in other countries has always been a problem for
us.  The wide availability of PRI somewhat obviates this need, but
sometimes we can not justify the cost when we only need a few lines.

Generally you can tell by your bill :)

if the line is called a trunk, it will be groundstart, if it is called a 
line it will be loopstart.

around here trunks are a few bucks more a piece with absolutely no value 
add that I can see.




At 04:05 PM 6/17/2003 -0700, you wrote:
>Hello Astrites,
>
>I was just about to send out a long email about not being able to detect 
>hang-up with my CAC II FXO module on my PSTN POTS lines.  I had tried many 
>configurations.  I had attached a toner to the line to see if I was 
>getting this "disconnect supervision" signal after hang-up. 
(toner has a
>line powered light in the off position)  It seemed that I was getting the 
>signal, as:
>
>     The light was steady on onhook
>     When the line rang the light dimmed.
>     When I picked up the line stayed dim (If I remember correctly)
>     When the other end hung up the light stayed on
>     Then turned off momentarily a few seconds later.  (I suspected this 
> was "disconnect supervision")
>
>Anyway asterisk never detected hang-up.  Everything else worked.  I was 
>frustrated as hell.
>
>After a few days of trying everything, I tried to set my CAC II FXO module 
>to Groundstart and configured zaptel.conf and zapata.conf to groundstart 
>signaling.
>
>Voila!  Everything work!
>
>The question is how does groundstart and loopstart work?  How was I able 
>to have a somewhat working system using loopstart when it seems that the 
>phone company signaling was groundstart?  Can I assume that my lines are 
>indeed groundstart?
>
>I am really happy that it works.  I can now begin the process of 
>deployment with a much greater feeling of security.
>
>Jason
>
>
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Thanks for the responses.

Here is an update on my zap groundstart, loopstart, "disconnect
supervision" woes.  Apparently, the groundstart mode in the CAC FXO module
works on loopstart lines.  I still don't understand how and why.

I have loopstart lines.

The only way "disconnect supervision" works on my system is if I set
the FXO module to groundstart.  However!  There is a big caveat.  In groundstart
mode, incoming caller ID stops working!  This is something I am going to have to
live with for now as disconnecting the line on hang-up is far more important
than caller ID.

I have no idea if the caller ID problem is a problem with CAC FXO modules or the
zap channel software or the fact that we are using groundstart signaling on a
loopstart line.

I can confirm that this is the behavior with both CAC I and CAC II units as I
have a CAC II unit and I spoke with Michael on this list who has a CAC I unit. 
Both of us are in the same predicament.

Anyway, I hope others find this info useful.  If anyone has any other ideas on
how I can get my caller ID to work I would be really excited about that.


Thanks,
Jason

PS: I have seen people mention that, when you have many lines, PRI is cheaper. 
This is not our case at all.  San Francisco.  We have eight lines at the cost of
$0.01 per line.  All we pay for really is the call time.

  ----- Original Message ----- 
  From: Surfer Dude 
  To: asterisk-users@lists.digium.com 
  Sent: Tuesday, June 17, 2003 4:05 PM
  Subject: [Asterisk-Users] Question :: groundstart and loopstart


  Hello Astrites,

  I was just about to send out a long email about not being able to detect
hang-up with my CAC II FXO module on my PSTN POTS lines.  I had tried many
configurations.  I had attached a toner to the line to see if I was getting this
"disconnect supervision" signal after hang-up.  (toner has a line
powered light in the off position)  It seemed that I was getting the signal, as:

      The light was steady on onhook
      When the line rang the light dimmed.
      When I picked up the line stayed dim (If I remember correctly)
      When the other end hung up the light stayed on
      Then turned off momentarily a few seconds later.  (I suspected this was
"disconnect supervision")

  Anyway asterisk never detected hang-up.  Everything else worked.  I was
frustrated as hell.

  After a few days of trying everything, I tried to set my CAC II FXO module to
Groundstart and configured zaptel.conf and zapata.conf to groundstart signaling.

  Voila!  Everything work!

  The question is how does groundstart and loopstart work?  How was I able to
have a somewhat working system using loopstart when it seems that the phone
company signaling was groundstart?  Can I assume that my lines are indeed
groundstart?

  I am really happy that it works.  I can now begin the process of deployment
with a much greater feeling of security.

  Jason

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