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You got me interested in this topic so I started doing some research.
There is a discussion on the asterisk-dev list about adding true busy
support to the Zaptel module. As it currently stands, when a call
comes in on a PRI channel while asterisk is shutting down asterisk
sends a signal back effectively rejecting the call, but the Telco sees
it as Asterisk answering the call. What needs to happen is a mechanism
needs to be implemented that will place the the channel in the off-hook
state after the active call hangs up until the PRI can be truly taken
down. I'm not a coder so I have no idea how to begin implementing
that, but I suspect it would not bee too difficult for a coder to go in
and take a couple of the pieces of code that answer or dial on channel
and make an "hook state" function.<br>
<br>
-Brent<br>
<br>
Andrew Smith wrote:
<blockquote cite="mid:001001c86fe1$0440a7d0$0f02000a@andrewslapvbox"
type="cite">
<meta http-equiv="Content-Type" content="text/html; ">
<meta content="MSHTML 6.00.6000.16587" name="GENERATOR">
<div dir="ltr" align="left"><span class="483093714-15022008"><font
color="#0000ff" face="Arial" size="2">Yes the 'stop gracefully' is
what effectively blocks the calls as the telco seems to take it as we
are answering the calls instead of seeing them as busy.</font></span></div>
<span class="483093714-15022008">
<div dir="ltr" align="left"><br>
<font color="#0000ff" face="Arial" size="2">I will look at
implementing some sort of way of busying out all the zaptel channels,
so that we eventually busy out all 120 channels (4x E1) and then can
cleanly take the server offline while our telco presents the calls to
the next Asterisk servers correctly.</font></div>
<div dir="ltr" align="left"> </div>
<div dir="ltr" align="left"><span class="483093714-15022008"><font
color="#0000ff" face="Arial" size="2">This would be a great way of
busying out the server for maintenance while still allowing our inbound
calls.</font></span></div>
<div dir="ltr" align="left"><font color="#0000ff" face="Arial"
size="2"><span class="483093714-15022008"></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" face="Arial"
size="2"><span class="483093714-15022008">Many thanks,</span></font></div>
<div dir="ltr" align="left"><font face="Arial"><font color="#0000ff"><font
size="2"><span class="483093714-15022008">Andrew</span></font></font></font><span
class="483093714-15022008"></span></div>
</span><br>
<div class="OutlookMessageHeader" dir="ltr" align="left" lang="en-us">
<hr tabindex="-1"><font face="Tahoma" size="2"><b>From:</b>
<a class="moz-txt-link-abbreviated" href="mailto:asterisk-users-bounces@lists.digium.com">asterisk-users-bounces@lists.digium.com</a>
[<a class="moz-txt-link-freetext" href="mailto:asterisk-users-bounces@lists.digium.com">mailto:asterisk-users-bounces@lists.digium.com</a>] <b>On Behalf Of </b>Brent
Davidson<br>
<b>Sent:</b> 15 February 2008 00:30<br>
<b>To:</b> Asterisk Users Mailing List - Non-Commercial Discussion<br>
<b>Subject:</b> Re: [asterisk-users] ISDN PRIs and taking a server
down formaintenance - blocking issue<br>
</font><br>
</div>
Correct me if I'm wrong, but as I understand it your issue is that when
you give Asterisk the "stop gracefully" command it waits until all
active calls have finished before it takes the ISDN down but gives busy
signals to new incoming calls on idle channels. If this is the case
then it would seem that Asterisk is actually answering the call on the
incoming channel and playing a busy signal. From reading a couple of
threads on another list it appears this is the case (Google: Asterisk
"busy out" PRI to find the discussion). There also appears to be some
interest in making a function do what you need in the future.<br>
<br>
For the time being, however, a simple solution would be to create a
temporary dial-plan that follows each outgoing hangup with a "dial"
command to either a test number or some other service that will just
keep playing audio down the line and not hangup. (You'd probably need
to set some variable to know which channels had been "busied") When you
need to take down a server, load this dial plan and wait for all
channels to call the "busy" number, then hang them all up and issue a
"stop now".<br>
<br>
It's a messy solution, but it's all I can think of without hacking
code. The only other way I'd know would be to hack the code for the
dial or answer command and build another command that simply takes the
channel off-hook and leaves it there.<br>
<br>
Good luck,<br>
Brent Davidson<br>
<br>
Lyle Giese wrote:
<blockquote cite="mid:47B4D278.5000001@lcrcomputer.net" type="cite">If
you take Asterisk down, the PRI should go down as the D channel is
down. Then the telco should KNOW that there is trouble with the PRI
and those channels are in trouble busy and not availible. If the telco
still tries to push a call to a channel on a PRI that is down, then the
telco is at fault.<br>
<br>
Lyle<br>
<br>
Matt wrote:
<blockquote
cite="midc11d02530802141325g5f31dc9anff7ad4a24033ffd4@mail.gmail.com"
type="cite">That does sound like what is happening.. Telco knows
channel 1-23 are not busy (so far as they are concerned), however.. so
far as you are concerned, they are busy.. so telco sends the call
down... but the equipment doesn't take it.<br>
<br>
I would *think* the Telco could keep trying channels down the hunt
group, but maybe not? We have, in the past, seen this issue with our
dial-up modem banks.. especially if I would take one offline.
However, it is not a big enough issue (i.e. we don't take things down
that often) for me to look into it fully.<br>
<br>
<div class="gmail_quote">On Thu, Feb 14, 2008 at 4:07 PM, Don
Kelly <<a href="mailto:dk@donkelly.biz" moz-do-not-send="true">dk@donkelly.biz</a>>
wrote:<br>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div vlink="blue" link="blue" lang="EN-US">
<div>
<p><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; color: navy; font-family: Arial;">I think the
problem is that the telco presents the call on a specific channel, then
zaptel tells it that the channel is busy.</span></font></p>
<p><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; color: navy; font-family: Arial;"></span></font> </p>
<p><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; color: navy; font-family: Arial;">We need to
be able to tell the telco that each unused channel on a given span is
unavailable, and it will determine that the others are in use and will
present the call on a channel on another span.</span></font></p>
<p><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; color: navy; font-family: Arial;"></span></font> </p>
<p><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; color: navy; font-family: Arial;">A rather
ugly work-around (since Andrew seems to have lots of channels
available, and one would assume that maintenance of this nature would
occur during slow periods) would be to make calls to a DID in the same
trunk group on all "idle" channels on the span shutting down then, when
all channels on the span are "in use" and none of them are doing
anything useful, take the span down hard so the telco will divert all
calls to another span.</span></font></p>
<div>
<p style="margin-bottom: 12pt;"><font color="navy"
face="Times New Roman" size="2"><span
style="font-size: 10pt; color: navy;"> --Don<br>
<br>
Don Kelly<br>
PCF Corp<br>
Real Support for your Virtual Office TM<br>
651 842-1000<br>
888 Don Kell(y)<br>
651 842-1001 fax<br>
<br>
</span></font></p>
</div>
<div>
<div style="margin-left: 0.5in; text-align: center;"
align="center"><font face="Times New Roman" size="3"><span
style="font-size: 12pt;">
<hr align="center" size="2" width="100%"> </span></font></div>
<p style="margin-left: 0.5in;"><b><font face="Tahoma" size="2"><span
style="font-weight: bold; font-size: 10pt; font-family: Tahoma;">From:</span></font></b><font
face="Tahoma" size="2"><span
style="font-size: 10pt; font-family: Tahoma;"> <a
href="mailto:asterisk-users-bounces@lists.digium.com" target="_blank"
moz-do-not-send="true">asterisk-users-bounces@lists.digium.com</a>
[mailto:<a href="mailto:asterisk-users-bounces@lists.digium.com"
target="_blank" moz-do-not-send="true">asterisk-users-bounces@lists.digium.com</a>]
<b><span style="font-weight: bold;">On Behalf Of </span></b>Matt<br>
<b><span style="font-weight: bold;">Sent:</span></b> Thursday,
February 14, 2008 2:28 PM
<div class="Ih2E3d"><br>
<b><span style="font-weight: bold;">To:</span></b> Asterisk
Users Mailing List - Non-Commercial Discussion<br>
</div>
<div>
<div class="Wj3C7c"><b><span style="font-weight: bold;">Subject:</span></b>
Re: [asterisk-users] ISDN PRIs and taking a server down formaintenance
- blocking issue</div>
</div>
</span></font> </p>
</div>
<div>
<div class="Wj3C7c">
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;"></span></font> </p>
<p
style="margin-bottom: 12pt; margin-left: 0.5in; margin-right: 0in;"><font
face="Times New Roman" size="3"><span style="font-size: 12pt;">Honestly..
this sounds like a telco issue. I understand what the other person
is saying about the PRI still being technically up... BUT... if the
channel is BUSY/BLOCKED/WHATEVER, the Telco should be forwarding the
call to the next available channel, which they clearly are not doing.</span></font></p>
<div>
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;">On Thu, Feb 14, 2008 at 8:29
AM, Andrew Smith <<a href="mailto:andrews@meadeplc.com"
target="_blank" moz-do-not-send="true">andrews@meadeplc.com</a>>
wrote:</span></font></p>
<div>
<p style="margin-left: 0.5in;"><font face="'Times New Roman'"
size="3"><span style="font-size: 12pt;">Hi Tim,</span></font></p>
<p style="margin-left: 0.5in;"><font face="'Times New Roman'"
size="3"><span style="font-size: 12pt;">Imagine the scenario where we
had 10x Asterisk servers, with calls presenting sequentially starting
from the first server, then server two, etc.</span></font></p>
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;"></span></font> </p>
<p style="margin-left: 0.5in;"><font face="'Times New Roman'"
size="3"><span style="font-size: 12pt;">If we took down the first
server for maintenance with 'asterisk -rx stop gracefully' we then will
block all incoming calls to all servers as our telco will simply relay
the BUSY back to the caller. If there are a number of calls on the
first server that continue for another 20 minutes, then all inbounds
are blocked for that period of time.</span></font></p>
<div>
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;"></span></font> </p>
</div>
<div>
<p style="margin-left: 0.5in;"><font face="'Times New Roman'"
size="3"><span style="font-size: 12pt;">We are finding at present we
have to look at the calls on the server and make a decision if we are
busy to simply reboot the server and hence lose calls. Not ideal but
then we don't end up blocking our inbounds.<br>
<br>
What I was hoping to do was find a way to cause the telco to present
the call to the next ISDN30 and therefore would allow us to cleanly
take down an Asterisk server for maintenance without causing this
issue. In a sense to put the ISDN30 into alarm mode while still
continuing the active calls.</span></font></p>
</div>
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;"></span></font> </p>
<p style="margin-left: 0.5in;"><font face="'Times New Roman'"
size="3"><span style="font-size: 12pt;">Do you know if this is at all
possible, even if we considered patching zaptel to add this
functionality or does the telco rely on the entire PRI being in alarm
before it presents the call to the next ISDN30 ? This would allow us to
run maintenance on our servers during busy periods without causing
disruption, and would be an excellent feature.<br>
<br>
Many thanks,</span></font></p>
<p style="margin-left: 0.5in;"><font face="'Times New Roman'"
size="3"><span style="font-size: 12pt;">Andrew</span></font></p>
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;"></span></font> </p>
<div style="margin-left: 0.5in; text-align: center;"
align="center"><font face="Times New Roman" size="3"><span
style="font-size: 12pt;">
<hr align="center" size="2" width="100%"> </span></font></div>
<p
style="margin-bottom: 12pt; margin-left: 0.5in; margin-right: 0in;"><b><font
face="Tahoma" size="2"><span
style="font-weight: bold; font-size: 10pt; font-family: Tahoma;">From:</span></font></b><font
face="Tahoma" size="2"><span
style="font-size: 10pt; font-family: Tahoma;"> <a
href="mailto:asterisk-users-bounces@lists.digium.com" target="_blank"
moz-do-not-send="true">asterisk-users-bounces@lists.digium.com</a>
[mailto:<a href="mailto:asterisk-users-bounces@lists.digium.com"
target="_blank" moz-do-not-send="true">asterisk-users-bounces@lists.digium.com</a>]
<b><span style="font-weight: bold;">On Behalf Of </span></b>Tim
Nelson<br>
<b><span style="font-weight: bold;">Sent:</span></b> 13
February 2008 18:12<br>
<b><span style="font-weight: bold;">To:</span></b> Asterisk
Users Mailing List - Non-Commercial Discussion<br>
<b><span style="font-weight: bold;">Cc:</span></b> <a
href="mailto:asterisk-users@lists.digium.com" target="_blank"
moz-do-not-send="true">asterisk-users@lists.digium.com</a><br>
<b><span style="font-weight: bold;">Subject:</span></b> Re:
[asterisk-users] ISDN PRIs and taking a server down for maintenance -
blocking issue</span></font></p>
<div>
<div>
<p
style="margin-bottom: 12pt; margin-left: 0.5in; margin-right: 0in;"><font
face="Times New Roman" size="3"><span style="font-size: 12pt;">Even if
* is shutdown, zaptel is still running and your ISDN channels are still
technically up. Shutting down zaptel should close the channels and put
those circuits into alarm mode.<br>
<br>
Tim Nelson<br>
Systems/Network Support<br>
Rockbochs Inc.<br>
(218)727-4332<br>
<br>
----- Original Message -----<br>
From: "Andrew Smith" <<a href="mailto:andrews@meadeplc.com"
target="_blank" moz-do-not-send="true">andrews@meadeplc.com</a>><br>
To: <a href="mailto:asterisk-users@lists.digium.com" target="_blank"
moz-do-not-send="true">asterisk-users@lists.digium.com</a><br>
Sent: Wednesday, February 13, 2008 12:03:51 PM (GMT-0600)
America/Chicago<br>
Subject: [asterisk-users] ISDN PRIs and taking a server down for
maintenance - blocking issue</span></font></p>
<div>
<div>
<p style="margin-left: 0.5in;"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Hi there,</span></font></p>
</div>
<div>
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;"></span></font> </p>
</div>
<div>
<p style="margin-left: 0.5in;"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">I currently have multiple
Asterisk servers using Sangoma A104d Quad ISDN E1s.</span></font></p>
</div>
<div>
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;"><br>
</span></font><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Basically our telco is
presenting calls in order of the ISDNs on our servers.</span></font></p>
</div>
<div>
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;"></span></font> </p>
</div>
<div>
<p style="margin-left: 0.5in;"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">SERVER1=1,2,3,4<br>
SERVER2=5,6,7,8</span></font></p>
</div>
<div>
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;"></span></font> </p>
</div>
<div>
<p style="margin-left: 0.5in;"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">We have redundancy in
that if SERVER1 is shutdown then each ISDN PRI is in alarm and the
calls will then presented to PRIs 5,6,7,8 on SERVER2.<br>
<br>
If I have to take SERVER1 offline for maintenance (asterisk -rx
shutdown gracefully) any incoming calls receive a BUSY tone.<br>
<br>
What I would like to know is if there is anyway to get around this and
not send a BUSY back to our callers and somehow allow our telco to
present calls immediately to SERVER2.<br>
<br>
Anyone have any ideas or are we stuck with this behaviour until the
calls drop to 0 and Asterisk shuts down ?<br>
<br>
Thanks,<br>
Andrew</span></font></p>
</div>
<div>
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;"></span></font> </p>
</div>
<div>
<p style="margin-left: 0.5in;"><font face="Times New Roman"
size="3"><span style="font-size: 12pt;"></span></font> </p>
</div>
</div>
</div>
</div>
</div>
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