[Asterisk-Users] Qs about FXO/FXS cards

[brian at txshirts.com]

I hate to ask the obvious....

But what's your power quality like?  Is the system on a UPS?

UPS supplied power makes a huge difference in system stability.  I
wouldn't run a server for anything (including testing) without it.

Second, what class of hardware?  You do get what you pay for and
"flakiness" can often be traced to power issues.

>From what I can tell the Digium hardware does some signal processing
magic by relying heavily on system power and cpu power.

The first clue here is the 12v plug to provide dial tone/ring to your
ATAs.

BTW, Ring on a analog phone is typically 90vAC.  Dial tone is @48V.  So
if you put a bunch of analog devices in you are begging for headaches.
I learned those numbers after being shocked.  I don't strip phone wire
with my teeth anymore.  Shame on me for being lazy.

I'm a firm believer in not running production systems on bargain
hardware.  I had nothing but grief out of my desktop class and generic
trash systems.  And yes, Shuttle is generic trash, as is ASUS, and A
Open and a host of other Taiwan Special stuff.  The way you save money
in those systems is by making thinner PCB's which will drive you insane
trying to troubleshoot.  One tweak of your case and you can "lose" some
contacts.  At any rate, judge a circuit by it's thickness.  Trash is
like paper and flexes.  Quality is thick and will cut you before it
bends.

I'm running older, but solid hardware and not seeing any issues.  I'm
using a Compaq Proliant 1850R Gen1 dual PII 400 with 512MB ram, GB
ethernet, and SATA Hardware RAID.  Cheap, efficient, redundant.  And for
a Debian box, good enough.  Initial testing with TOP shows that one ATA
to VOIP connection costs 4% of CPU to start up and then 2% to carry.
Considering we have 10 handsets and 10 employees with 4 lines and
normally no more then 2 people on the POTS lines.... I think we're in
good shape.  If you're planning to run a E*trade call center, you may
want more substantial hardware.  If you are planning the Mom&Pop
Voicematrix @Home you may be just fine with a old Proliant.  They have
redundant power supplies and they are cheap and indestructible.
Although it's a bit loud to keep in the bedroom.  :)

Don't get me wrong, I'm not trashing your hardware.  If you can run
cheap bargain hardware and get it to work great.  But my experience has
been that I lost my A** on generic knockoff stuff when I sold PC's for a
living.  I spent a lot of time chasing errors that I never could find
the cause of.  Granted my webservers run Windows... And this is a linux
app... But I see uptime in the range of months with Proliant hardware.
That *is* remarkable for MSFT products.  

Anyhow that's my two cents..... I wonder if there is a correlation
between hardware class and issues with TDM boards? 


Brian Greul
Texas Shirt Company
www.txshirts.com
713-802-0369 / 713-861-6261 (fax)

-----Original Message-----
From: Michael Welter [mailto:mike at introspect.com] 
Sent: Saturday, January 01, 2005 5:15 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [Asterisk-Users] Qs about FXO/FXS cards

brian at txshirts.com wrote:
> What exactly are people seeing when they have "issues" with their TDM 
> card?
> 
> 
> Brian Greul
> Texas Shirt Company
> www.txshirts.com
> 713-802-0369 / 713-861-6261 (fax)

Since you asked, and since I'm well into this bottle of Merlot on New
Year's day:

1.  Power alarms.  WTF does that mean?  Wish I had some support docs.

2.  On bootup, "Excessive leakage module x, ProSLIC failed Auto
Configuration".  Again, WTF?  Reboot and it's ok.  But, just a reboot
after driving 100+ miles to the client site is not a good option.

3.  On bootup, a LED won't light.  When zapata gets to it, it can't find
the channel.  Usually means a complete power cycle to get it to work.

4.  A TDM card that isn't recognized at all.  DOA.

5.  Impedience matching to eliminate hummmmmmmmmm?

I'm calling Matt on Monday, and hopefully he'll RMA these cards.

I hope that everyone that has a life is out enjoying the New Year.

Cheers,
Mike



--
Michael Welter
Introspect Telephony Corp.
Denver, Colorado US
+1.303.674.2575
mike at introspect.com
www.introspect.com
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