[Asterisk-Users] Terrible crackling on analogue line and X100Pcard

[Rich Adamson]

> > Okay. There are two fairly small integrated circuits on the board.
> > Can you post the part numbers on those chips?
> 
> Not at the moment, unfortunately. The card is in a datacentre 200 miles 
> away. However, and while I appreciate that you can't read anything from 
> this, but this is the card:
> 
> http://i24.ebayimg.com/01/i/02/c3/8b/43_1.JPG
> 
> (the same Ebay vendor is selling dozens of them)
> 
> > NMI = non maskable interrupt (or somthing like that). Those messages
> > would suggest there is a problem with that card and the wcfxo driver.
> 
> Right.
> 
> > The "mode is FCC" is saying the zaptel drivers are assuming a
> > card that matches US telco standards. Again, without the chip set
> > numbers, I can't tell if that card will work correctly in the UK.
> > If it does not support UK standards, not likely you'll ever get
> > the echo to go away.
> 
> Sounds like I've bought a hooky card then :(
> 
> > Okay, then there is about a 90% chance the card's chip set was
> > designed for the US telco standards. I'll be able to tell more
> > once you post those part numbers.
> 
> It's going to be a couple of weeks before I can do that, unfortunately.
> 
> > Are you using a "opermode=UK" or anything like that in /etc/zaptel.conf?
> 
> No. Should I try that or do you not think it'll make that much difference in 
> light of the findings above?
> 
> > It would appear you have several interrupts that aren't being used.
> > Have you tried looking at the bios setup to see if you can disable
> > any unused interrupts (like 3 for com1 port)?
> 
> Yes I tried all that. Even freeing up other interrupts caused the system to 
> fail to boot. I didn't understand it.
> 
> > If there is nothing in the bios relative to configuring interrupts, then
> > you only choice is to move the card to other slots in hope of
> > finding one that assigns a different interrupt.
> 
> Now that I didn't try.
> 
> > There is at least a better then 50% chance sharing the interrupt
> > between the wcfxo driver and the raid controller (#11) is causing
> > at least some of the crackling noise. You might try establishing
> > a call and do a large file copy (to exercise the disk) to see if
> > disk activity causes the noise.
> 
> I tried this and it made no noticeable difference. The crackling's always 
> quite bad to start with, and since RAID controllers are basically small 
> computers themselves it probably stands to reason that activity will be 
> pretty much constant.
> 
> [zttest]
> >> Is that good?
> >
> > Yes, that looks good.
> 
> That's something at least!
> 
> > You might try going back to an earlier version (or cvs head) to
> > see if that has any impact on the noise.
> 
> I think that in light of what you've advised above I don't think this is the 
> problem. I also completely disagree with regressing to former versions of 
> software to hack something into working, since I might actually need a 
> feature or bugfix that's provided by the later version in order to have 
> something else working!
> 
> So, here's what I think I'll do:
> 
> 1) I'm going to start with buying a genuine X100P, to eliminate the 
> possibility of cheapness affecting things. However, as I said, I'm having 
> tremendous trouble sourcing one. Does anyone know of any outlets in the UK 
> who supply them? I've seen them for sale on several US websites, but I'm 
> going to assume that they'll only work with US telcos?
> 
> 2) Once I've got one, I'll have another stab at the interrupt mess again. 
> I'll try to move the card between PCI slots and have another, more 
> structured, session with the BIOS.
> 
> Sound like a plan?

Sounds reasonable for starters.

Somewhere in your plan I'd really suggest implementing another version
at least on a temp basis as one mechanism to rule out a problem with
your current version. It's not that hard really.

Also, keep in mind the x100p cards were designed years ago as a modem
(not a voip/pstn interface). Having been around this list for over a
year now, I don't remember hearing/seeing anyone say they found a x100p
card or compatible that truly supports the UK standards. I'd have to 
guess the OEMs targeted the US modem market at that time, so mucking
around with other x100p compatibles are just as likely to result in
time consuming frustration.

Some of the compatible cards use an Intel chipset. If you look at the
Intel specs, Intel had two different chipsets on their cards; one
targeted for the US market, and the other for limited non-US markets.
Even if you find a card targeted for the non-US market, I wouldn't
bet a nickle the interrupt issues shown in your output will be 
addressed.

The TDM400 card (with appropriate modules) is the replacement for the
x100p, and the chipset in use on those modules _do_ support many different
international standards. The early versions of the TDM card had several
problems (output of dmesg showed Wildcard TDM400P REV E/F as an example),
however the current version (Wildcard TDM400P REV H) seems to be far
more stable. (I just replaced my old card yesterday with a new one
provided by digium as an in-warrantee RMA replacement.)

Even though the TDM card will cost more, you're more likely to end up
with something far more usable then the old x100p card. I've got two
of the digium x100p cards on my shelf.  You should also consider 
that no new development/maintenance work is happening on the x100p 
driver (wcfxo).

I've heard others say the TDM card is available from UK suppliers, but
I'd make certain you get the latest version of the card and not one
of the earlier models that happens to be sitting on your supplier's
shelf. Seems that is a problem with several US suppliers, and most of
them don't have a clue what version they actually are selling. Since
the RMA process is very time consuming (and probably expensive for
overseas turn around), force your supplier into checking the version
otherwise don't buy it.

As others have noted on this list, in the UK you'll have far better
service using isdn facilties then what you'll get from any analog
interface. So, somewhere along your decision tree you'll have to
decide how much time/money you want to pure into analog vs isdn.