[VoIP] Tandem Stacking over Asterisk

[Donald Froula]

I also changed rxwink=150. It now takes 150 ms. of
2600 to seize the trunk. This also lengthens the
forward disconnect time on each link in the forward
stack, so you can hear the individual cheeps of 2600
as the stack is torn down. It's slow enough you can
count the links.

Don

--- Donald Froula <dfroula at sbcglobal.net> wrote:

> I changed the setting of "toneduration" in
> /etc/zapata.conf from 68 ms. to 100ms. This
> increases
> the duration of the MF tones on the SF trunk group
> during call setup, but also increases the length of
> regenerated DTMF tones sent down the line. This
> enhances the "flash forward" effect on a tandem
> stack
> by extending the propagation time through each link.
> 
> The reason one gets a hook-flash effect when dialing
> DTMF through the stack is that The ATA receives the
> DTMF digit, converts it to a SIP message, Zaptel
> converts back to audio on the first SF trunk link,
> Zaptel converts back to an internal message on the
> receiving end, then back to analog DTMF on the next
> link and so on. This adds a 100 ms. delay for each
> link on each flash of a DTMF digit down the stack.
> 
> Don
> 
> --- Donald Froula <dfroula at sbcglobal.net> wrote:
> 
> > This actually sound pretty amazing while listening
> > on
> > the far end, if one dial an extension on the last
> > loop. When the originating end goes on-hook, you
> can
> > hear the string of kercheeps as the call
> > disconnects,
> > one for each link. If the originating end taps a
> > touch
> > tone digit, you can hear a series of clicks as the
> > tone propagates down the stack. Sounds pretty much
> > like the Classic Stacking recording!
> > 
> > If you want to try, here's how:
> > 
> > - Dial my ProjectMF trunk on 1-762-2601 (or
> > 1-762-2602, skipping the net two steps, for those
> > without a blue box)
> > - Blow off the ringing with 2600
> > - After the wink, dial KP-2602-ST
> > - Wait for the dial tone
> > - Dial 2602 with the DTMF pad of the phone
> > - Wait for another dial tone
> > - Dial 2602 with the DTMF pad
> > - (Repeat X times, up to 23 times, as desired)
> > - On the last dial tone, dial a number on CNET
> with
> > 011+CC_Number, again with the DTMF pad
> > - Answer the ringing phone. You are now talking to
> > yourself over X number of SF trunk links
> > - Hit a touch tone digit onthe originating phone.
> > Listen to it flash down the stack.
> > - Hang up. Hear the stack disconnect with a cheep
> of
> > 2600 for each link
> > 
> > Notice how the connection takes longer to return
> the
> > dial tone on each loop through the stack, as the
> > audio
> > delay on the forward MF (which you can't hear)
> gets
> > longer and longer.
> > 
> > Regardless of how you come in. you can blow the
> call
> > off in the forward direction with 2600 and hear
> the
> > stack disconnect on the far side.
> > 
> > Much fun!
> > 
> > Don
> > 
> > PS - For those without MF and 2600, I set up
> direct
> > access to the SF/DISA arrangement on 1-762-2602
> > 
> > Note, if others are trying this, your available
> > trunk
> > pool may be less than 24.
> > 
> > --- Donald Froula <dfroula at sbcglobal.net> wrote:
> > 
> > > I hit upon an approach to try this trunk
> stacking
> > > thing through my TDM-Over-Ethernet SF/MF trunks.
> I
> > > set
> > > up two extensions to go to DISA over the trunks.
> > > What
> > > I do is dial the extension that goes over the
> > trunks
> > > (similar to my 1-762-2601 number), but instead
> of
> > > programming the number that gives ringback in
> the
> > > Dial
> > > command, I call another extension with the DISA
> > > application that returns a dial tone.
> > > 
> > > 2602 => 1,Dial(ZAP/g1/9999)
> > > 
> > > 9999 => 1,DISA(password|from-internal)
> > > 
> > > I then dial the same number again (2602), which
> > > seizes
> > > the next line and gives a DISA dial tone again.
> > This
> > > is all via DTMF, so, yes, I am cheating.
> However,
> > > the
> > > call setup on each loop through the trunk group
> is
> > > via
> > > 2600 and MF.
> > > 
> > > I saturated all 24 lines of the trunk group this
> > > way,
> > > dialing one of my Evan Doorbell recordings on
> the
> > > last
> > > trunk. The audio was looping through all 24
> > > SF-controlled trunks. Both sides of the
> connection
> > > being on the same switch, I only noticed slight
> > > degradation in the audio. I blew off the call
> with
> > a
> > > chirp of 2600. This sounded exactly like blowing
> > off
> > > a
> > > call on a single trunk, except for the 24
> > disconnect
> > > mrssages that flew by on the Asterisk console.
> > > 
> > > Now, if the looping could be done through
> another
> > > ProjectMF switch, it might sound interesting.
> > > 
> > > Don
> > > 
> > > --- Donald Froula <dfroula at sbcglobal.net> wrote:
> > > 
> > > > Mark, you asked about whether or not a 2600
> > audio
> > > > blip
> > > > might get propagated through the system for
> 2600
> > > > flashes less than rxwink in length. Actually,
> > they
> > > > would. The 2600 notch filter DSP code takes a
> > > > millisecond or so to kick in and out, creating
> > an
> > > > audible "blip" both on 2600 application and
> > > removal.
> > > > Although this has no effect on supervision,
> > being
> > > > purely an audio effect, it might provided
> > > something
> > > > like the old sound with the latency delay
> > through
> > > > VOIP.
> > > > 
> > > > Don
> > > > 
> > > > --- Donald Froula <dfroula at sbcglobal.net>
> wrote:
> > > > 
> > > > > Hi, Mark. Good to hear from you "down
> under",
> > > > > 
> > > > > I corrected the trunk-hang problem by a
> patch
> > I
> > > > > added
> > > > > to Asterisk that restored 2600 supervision
> > based
> > > > > upon
> > > > > steady-state 2600. It sounds odd, but
> seizure
> > of
> > > > the
> > > > > trunk with the original set of patches was
> > based
> > > > on
> > > > > REMOVAL of steady 2600. Applying steady 2600
> > > after
> > > > > seizure did not disconnect the call. This
> was
> > to
> > > > > allow
> > > > > the user to 'box another call after the
> > previous
> > > > far
> > > > > end call disconnected. Evan Doorbell calls
> > this
> > > a
> 
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