[Asterisk-Users] An anniversary and a lament for FXOs

[Chad Scott]

Just to provide some more votes in the X100P column, I have an X100P as 
my telco interface and have had absolutely no echo problems at all.  
I've called from it and I've called into it and held long conversations 
and never heard an echo even once.

It's not a host CPU issue as Asterisk is running on a 
barely-glued-together old Dell 1GHz P3 with 256MB of RAM and something 
like 40GB of disk space.

I think the rxgain and txgain are important... if you jack those up too 
much, the telco echo can can't keep up anymore and you hear far-side 
echo.  I've seen Asterisk's echo can work pretty effectively at all 
kinds of gain settings, but that was on a digital circuit (haven't 
screwed with my analog version at home too much).

At any rate, if you're having issues, I'd make sure echo cancellation 
is *on* both generally and during a bridged call.  If that's true, I'd 
set rxgain and txgain both to zero and see if the echo simply goes 
away.  If so, then I'd adjust the gain upward as needed to equalize the 
line until it sounds right or an echo appears and back off just 
slightly from that value.

On Nov 3, 2004, at 7:23 AM, Dave Henderson wrote:

> Hi Michael,
>
> You mention the X100P -- I agree, it's not a great card.  I've had all
> sorts of issues with mine, though I've lived with it for one of my
> not-so-important Asterisk PBXes.
>
> One device it seems you haven't tried is the Digium TDM400P with an FXO
> module...  I've used a pile of these, and have generally been very
> pleased with them.
>
> --
> Dave Henderson
> Customer Service Manager
> The IT Department, Inc.
>
> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of
> mgraves at mstvp.com
> Sent: November 3, 2004 10:14 AM
> To: Asterisk Group
> Subject: [Asterisk-Users] An anniversary and a lament for FXOs
>
> This week marks one year since I first setup an Asterisk server in the
> hopes of transitioning my home office to a total VoIP system. The
> process has been an incredible learning experience. I've tried numerous
> IP hard phones, eventually settling upon the Polycom IP600 as my 
> choice.
> I've also used multiple ATAs including all the Sipura products.
> Using Asterisk has been a challenge, a thrill and (when its working) a
> joy. However, the one thing that I am not satisfied with is the
> performance of the FXO interfaces that bring in my PSTN lines.
>
> I've tried X100p cards but found them horribly unreliable. I presently
> use Sipura SPA-3000s but they're only marginally better. How is it that
> my Panasonic 4 line SOHO phone system (KX-TG4000B) can have four 
> stable,
> reliable FXOs with no echo at all in a device with a total cost of
> <$500? It seems to me that there ought to be hardware available that
> behaves just as well, but bridges the PSTN to the SIP/IAX domain?
>
> I've read a lot on the list about how difficult designing FXOs can be,
> but that flies in the face of the fact that every small multi-line 
> phone
> system has them...and without expection those behave better than the
> devices I've been able to try with Asterisk. The Sipura SPA-3000 has
> several settings to adjust for line impedance and inductive/capacitive
> line loading....lots of settings, but it provides nowhere near the 
> basic
> performance of one of the lines on the Panasonic KSU. It's simply mind
> boggling.
>
> So, while I've posted with respect to FXOs previously, I must ask
> again....what FXO interface device can anyone recommend from real
> experience?
>
> Michael
>
> P.S.  -  I even investigated switching my lines to ISDN to get around
> the need for FXOs, but SBC won't do it where I live.
> --
> Michael Graves                           mgraves at pixelpower.com
> Sr. Product Specialist                          www.pixelpower.com
> Pixel Power Inc.                                 mgraves at mstvp.com
>
> o713-861-4005
> o800-905-6412
> c713-201-1262
>
>
>
>
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