[asterisk-biz] PRI dropped calls, D channel traces, and more

[Mitul Limbani]

Hi harry,

Over the past 1+ year I have encountered similar issue as u saying,  
bad HDLC and the line resets dropping all the calls on the line.

After diagnosis of each different case I got the following reasons:

1) the card is conflicting with some other resource on the pc, 90%  
time it conflicts with either the USB controller or Ethernet  
controller, try disabling these hardware or try different PCI slots or  
in some cases I have tried entirely different PC and the line drop  
issue disappeared.

Cat /proc/interupts

2) Use Xorcom's AstriBank although it is bit exp and doesnt have  
onboard echo cancellation v/s PCI cards but you dont have worry about  
PCI slots n stuff anymore, no line drop due to HDLC has been reported  
by any of my customers using the Xorcom hardware.

3) If you did 1 and still facing issue raise a support ticket with  
Sangoma they would definitely fix or provide cure

4) based on 1 and 3 you can go back to telco and get them to layout  
the Fibre once again from their junction box, coz then your line is  
failing due to physical disturbance in line, and this is something  
which the tester unit is capable to withstand, but not asterisk. So  
although they show you line perfectly ok on their tester units it  
would fail after unpredictable time delay on asterisk.(make sure you  
fix 1 and 3 before doing this or else you loose reputation in front of  
customer and telco both)

Let me know,

Regards,
Mitul Limbani,
Founder & CEO,
Enterux Solutions Pvt Ltd,
The Enterprise Linux Company(r),
http://www.enterux.com/


On 02-Apr-09, at 7:21, Harry McGregor <hmcgregor at biggeeks.org> wrote:

> Hi,
>
> We are having some issues with dropped calls on our combined voice/ 
> data
> T1 (ISDN PRI hand over of the voice channels).
>
> Our users are reporting frequent (3-10/day for an 8 person office)
> dropped calls, including calls with the other party being on a land  
> line.
>
> The telco keeps coming back that the line is clean.
>
> Anyone here have solid experience in reading through D-Channel  
> traces to
> figure out what is going on exactly, enough that we can either fix our
> Asterisk issue or push the telco for a fix.
>
> Most of the issues started when we switched from doing our own analog
> split out for fax (Sangoma T1 card, Sangoma Analog), to having our  
> telco
> split out the fax lines.
>
> We had issues with fax reliability on the sangoma pair (even though it
> had worked well for us in the past with other installs), and  
> switched to
> telco analog hand over for fax (which permitted the Windows SBS fax
> server to work, though we are getting a lot of cut off faxes).
>
> Environment is Asterisk 1.4.21 on Debian Lenny Kernel 2.6.26
>
> 01:06.0 Network controller: Sangoma Technologies Corp. A101 single- 
> port
> T1/E1 (rev 01)
> 01:07.0 Network controller: Sangoma Technologies Corp. A200/Remora
> FXO/FXS Analog AFT card
>
> -----
>
> We really need to get to the bottom of this fax issue.  We can provide
> logs, and we can provide supervised (screen),bastion host based SSH
> access to the asterisk system.
>
> I would like to keep the cost down of course, but can offer between  
> $150
> (looking at the logs, giving suggestions), up to $500 (if you can  
> truly
> solve the issue, and our users are happy).
>
>
>                                        Harry
>
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