[Out of curiosity] Why not use a voice modem for FXO?

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[Out of curiosity] Why not use a voice modem for FXO?

GillesToo
Hello

In case there are system developers out there with good experience writing modem softare, considering that...
1. even a cheap OpenVox PCI card starts at $90 for just one FXO port
2. even entry-level PC's theses days have ample CPU power especially when just used a basic server with Linux
3. we've been using so-called softmodems (ie. controller-less modems that offload processing to the computer's CPU) for over a decade and they sell for about $10 as OEM
4. and finally, Digium/Asterisk's Zaptel driver was precisely meant to run on cheap voice cards

... I was wondering why no one has gone forth and written a driver for this kind of hardware, which would be great for SOHO users to handle just one landline. Is it because the hardware is not standard enough, and writing this kind of driver takes a lot of work?

Thank you.
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Re: [Out of curiosity] Why not use a voice modem for FXO?

Brian West
What do you mean?  Anything that is zaptel compatible will work with OpenZAP/FreeTDM.  Even the cheap OpenVox single port FXO's.

/b

On May 26, 2010, at 8:37 AM, GillesToo wrote:

> ... I was wondering why no one has gone forth and written a driver for this
> kind of hardware, which would be great for SOHO users to handle just one
> landline. Is it because the hardware is not standard enough, and writing
> this kind of driver takes a lot of work?


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Re: [Out of curiosity] Why not use a voice modem for FXO?

GillesToo
Sorry: I mean that Zaptel doesn't work on softmodems, just Digium and Digium-compatible telephony cards. I don't see why softmodems couldn't handle the load of a single landline.

For instance, "U.S. Robotics USR5670 56Kbps PCI Bus (Plug & Play) Fax modem" sells for $17:

www.newegg.com/Product/Product.aspx?Item=N82E16825104001

Or maybe the hardware out there is just too diverse that writing a driver for this is a PITA?
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Re: [Out of curiosity] Why not use a voice modem for FXO?

Anthony Minessale
Even if you get it working the reward is not worth the effort.
You would experience a lot of echo and other problems and the time you spent working on it would
be better spent doing something more meaningful and using the money you received to buy a real TDM card or
better still, a FXO->SIP ATA.

On Wed, May 26, 2010 at 8:59 AM, GillesToo <[hidden email]> wrote:

What do you mean?  Anything that is zaptel compatible will work with
OpenZAP/FreeTDM.  Even the cheap OpenVox single port FXO's.


Sorry: I mean that Zaptel doesn't work on softmodems, just Digium and
Digium-compatible telephony cards. I don't see why softmodems couldn't
handle the load of a single landline.

For instance, "U.S. Robotics USR5670 56Kbps PCI Bus (Plug & Play) Fax modem"
sells for $17:

http://www.newegg.com/Product/Product.aspx?Item=N82E16825104001
www.newegg.com/Product/Product.aspx?Item=N82E16825104001

Or maybe the hardware out there is just too diverse that writing a driver
for this is a PITA?
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Re: [Out of curiosity] Why not use a voice modem for FXO?

Mike Tkachuk
In reply to this post by GillesToo
Hello GillesToo,

 Asterisk "X100P" is just Intel IA92 WinModem.
 This is the so-called "clone" X100P, you can buy it on ebay for 15$
 I used this last time like 5 years ago :)
 Main  problems  you'll  face  is echo and detecting line states (when
 remote party hangup or pick up a call)

Wednesday, May 26, 2010 4:37:08 PM, you wrote:


G> Hello

G> In case there are system developers out there with good experience writing
G> modem softare, considering that...
G> 1. even a cheap OpenVox PCI card starts at $90 for just one FXO port
G> 2. even entry-level PC's theses days have ample CPU power especially when
G> just used a basic server with Linux
G> 3. we've been using so-called softmodems (ie. controller-less modems that
G> offload processing to the computer's CPU) for over a decade and they sell
G> for about $10 as OEM
G> 4. and finally, Digium/Asterisk's Zaptel driver was precisely meant to run
G> on cheap voice cards

G> ... I was wondering why no one has gone forth and written a driver for this
G> kind of hardware, which would be great for SOHO users to handle just one
G> landline. Is it because the hardware is not standard enough, and writing
G> this kind of driver takes a lot of work?

G> Thank you.



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Re: [Out of curiosity] Why not use a voice modem for FXO?

Steve Underwood
In reply to this post by GillesToo
On 05/26/2010 09:37 PM, GillesToo wrote:

> Hello
>
> In case there are system developers out there with good experience writing
> modem softare, considering that...
> 1. even a cheap OpenVox PCI card starts at $90 for just one FXO port
> 2. even entry-level PC's theses days have ample CPU power especially when
> just used a basic server with Linux
> 3. we've been using so-called softmodems (ie. controller-less modems that
> offload processing to the computer's CPU) for over a decade and they sell
> for about $10 as OEM
> 4. and finally, Digium/Asterisk's Zaptel driver was precisely meant to run
> on cheap voice cards
>
> ... I was wondering why no one has gone forth and written a driver for this
> kind of hardware, which would be great for SOHO users to handle just one
> landline. Is it because the hardware is not standard enough, and writing
> this kind of driver takes a lot of work?
>
> Thank you.
>    
Despite a lot of hot air spouted to the contrary, very few people have
produced open source telephony code. None of those have so far been
motivated to produce the relevant driver, so today the only one
available is the Digium's own intel 536 driver in the zaptel/dahdi
distribution. If you would like to produce drivers for other common
chipsets, many people would be delighted. They just won't contribute.

Steve


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Re: [Out of curiosity] Why not use a voice modem for FXO?

Giovanni Maruzzelli
In reply to this post by Mike Tkachuk
On Wed, May 26, 2010 at 5:41 PM, Mike Tkachuk <[hidden email]> wrote:
> Hello GillesToo,
>
>  Asterisk "X100P" is just Intel IA92 WinModem.
>  This is the so-called "clone" X100P, you can buy it on ebay for 15$
>  I used this last time like 5 years ago :)
>  Main  problems  you'll  face  is echo and detecting line states (when
>  remote party hangup or pick up a call)

XP100 clones that you can buy cheap works decent if you use OSLEC line
echo cancellation (
http://www.rowetel.com/ucasterisk/oslec.html#install ).

Obviously, that will not give you the reliability, call flow analisys,
etc you can get from a "real" telephony card, or better an ATA, but
you can experiment with it and see if it can satisfy your needs (using
OSLEC for zaptel).


>
> Wednesday, May 26, 2010 4:37:08 PM, you wrote:
>
>
> G> Hello
>
> G> In case there are system developers out there with good experience writing
> G> modem softare, considering that...
> G> 1. even a cheap OpenVox PCI card starts at $90 for just one FXO port
> G> 2. even entry-level PC's theses days have ample CPU power especially when
> G> just used a basic server with Linux
> G> 3. we've been using so-called softmodems (ie. controller-less modems that
> G> offload processing to the computer's CPU) for over a decade and they sell
> G> for about $10 as OEM
> G> 4. and finally, Digium/Asterisk's Zaptel driver was precisely meant to run
> G> on cheap voice cards
>
> G> ... I was wondering why no one has gone forth and written a driver for this
> G> kind of hardware, which would be great for SOHO users to handle just one
> G> landline. Is it because the hardware is not standard enough, and writing
> G> this kind of driver takes a lot of work?
>
> G> Thank you.
>
>
>
> --
> Mike Tkachuk
>
>
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>



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Re: [Out of curiosity] Why not use a voice modem for FXO?

GillesToo
In reply to this post by Anthony Minessale
Anthony Minessale wrote
Even if you get it working the reward is not worth the effort. You would experience a lot of echo and other problems
I read somewhere that the reason for those problems people often have with X100P cards (such as echo or bad far-end disconnect supervision) is that most of them have they use the Silicon Labs DAA chips Si3012/Si3035 which is only good for use in countries that use the FCC standard; Countries that use the CTR21 standard (Europe, and others) require the Si3014/Si3034 chips, which support global line standards.

Anthony Minessale wrote
... and the time you spent working on it would be better spent doing something more meaningful and using the money you received to buy a real TDM card or better still, a FXO->SIP ATA.
I thought TDM cards were a better solution to connect an IP PBX to a landline. Why would you recommend an FXO-SIP ATA instead? And which brand/model of ATA is recommended for use with Freeswitch?
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Re: [Out of curiosity] Why not use a voice modem for FXO?

Anthony Minessale
It all depends, FXO is never truly reliable with all the disconnect supervision / hangup detection woes.
A FXO card works as well as it can but traditionally requires an echo canceler if you want quality that 
will not draw complaints from your best QA testers, your family for instance who expect identical
quality to the PSTN.  The Sangoma cards for instance have this.

The good thing about an ATA is that it's self-contained and translates everything into SIP for you when
you don't have room for hardware.

It's not worth cutting corners on telephone quality when, in the end, you will replace it once you get enough
complaints.




On Wed, May 26, 2010 at 3:26 PM, GillesToo <[hidden email]> wrote:


Anthony Minessale wrote:
> Even if you get it working the reward is not worth the effort. You would
> experience a lot of echo and other problems

I read somewhere that the reason for those problems people often have with
X100P cards (such as echo or bad far-end disconnect supervision) is that
most of them have they use the Silicon Labs DAA chips Si3012/Si3035 which is
only good for use in countries that use the FCC standard; Countries that use
the CTR21 standard (Europe, and others) require the Si3014/Si3034 chips,
which support global line standards.


Anthony Minessale wrote:
> ... and the time you spent working on it would be better spent doing
> something more meaningful and using the money you received to buy a real
> TDM card or better still, a FXO->SIP ATA.

I thought TDM cards were a better solution to connect an IP PBX to a
landline. Why would you recommend an FXO-SIP ATA instead? And which
brand/model of ATA is recommended for use with Freeswitch?
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Re: [Out of curiosity] Why not use a voice modem for FXO?

GillesToo
Anthony Minessale wrote
A FXO card works as well as it can but traditionally requires an
echo canceler if you want quality that will not draw complaints
Why do FXO cards generate echo issues while ATA don't? For instance, there are a lot of people complaining about echo with the Linksys 3102.

Anthony Minessale wrote
The good thing about an ATA is that it's self-contained and translates
everything into SIP for you when you don't have room for hardware.
Actually, that's why I prefer to use a PCI card instead of an ATA: No need for a transformer and a cable to connect the ATA to the Freeswitch server, and only one cable left to connect the PCI card to the wall plug. With non-techie customers, it seems like a safer solution.
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Re: [Out of curiosity] Why not use a voice modem for FXO?

Anthony Minessale
ok,

sure, we support a variety of cards.  I personally recommend sangoma.


On Wed, May 26, 2010 at 5:49 PM, GillesToo <[hidden email]> wrote:


Anthony Minessale wrote:
> A FXO card works as well as it can but traditionally requires an
> echo canceler if you want quality that will not draw complaints

Why do FXO cards generate echo issues while ATA don't? For instance, there
are a lot of people complaining about echo with the Linksys 3102.


Anthony Minessale wrote:
> The good thing about an ATA is that it's self-contained and translates
> everything into SIP for you when you don't have room for hardware.

Actually, that's why I prefer to use a PCI card instead of an ATA: No need
for a transformer and a cable to connect the ATA to the Freeswitch server,
and only one cable left to connect the PCI card to the wall plug. With
non-techie customers, it seems like a safer solution.
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Re: [Out of curiosity] Why not use a voice modem for FXO?

GillesToo
Thanks for the feeback.
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Re: [Out of curiosity] Why not use a voice modem for FXO?

Steve Underwood
In reply to this post by GillesToo
On 05/27/2010 06:49 AM, GillesToo wrote:
>
> Anthony Minessale wrote:
>    
>> A FXO card works as well as it can but traditionally requires an
>> echo canceler if you want quality that will not draw complaints
>>      
> Why do FXO cards generate echo issues while ATA don't? For instance, there
> are a lot of people complaining about echo with the Linksys 3102.
>    
ATAs contain echo cancellers. The SPA3102 contains one, but it seems to
be badly broken. The FXO cards are mostly dumb. Its up to host software
to provide functions like DTMF decoding and echo cancellation for them.
Try OSLEC with most FXO cards and you'll get great results.

> Anthony Minessale wrote:
>    
>> The good thing about an ATA is that it's self-contained and translates
>> everything into SIP for you when you don't have room for hardware.
>>      
> Actually, that's why I prefer to use a PCI card instead of an ATA: No need
> for a transformer and a cable to connect the ATA to the Freeswitch server,
> and only one cable left to connect the PCI card to the wall plug. With
> non-techie customers, it seems like a safer solution.
>    
Steve


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Re: [Out of curiosity] Why not use a voice modem for FXO?

Steve Underwood
In reply to this post by GillesToo
On 05/27/2010 04:26 AM, GillesToo wrote:

>
> Anthony Minessale wrote:
>    
>> Even if you get it working the reward is not worth the effort. You would
>> experience a lot of echo and other problems
>>      
> I read somewhere that the reason for those problems people often have with
> X100P cards (such as echo or bad far-end disconnect supervision) is that
> most of them have they use the Silicon Labs DAA chips Si3012/Si3035 which is
> only good for use in countries that use the FCC standard; Countries that use
> the CTR21 standard (Europe, and others) require the Si3014/Si3034 chips,
> which support global line standards.
>    
Most X100P clones don't use any kind of Silicon Labs chip. Whatever chip
they do use will probably not be programmed properly to match the line,
because the drivers don't support that. However, with the use of a
decent echo canceller you'll probably never notice. Use OSLEC with most
X100P cards on most lines around the world and the results should be
pretty good. The only things those X100P cards can't do, which some more
complex FXO cards can, is detect line current breaks and reversals. Most
lines around the world don't produce breaks or reversals so its not a
major issue. Everything else is down to what the host software does.

> Anthony Minessale wrote:
>    
>> ... and the time you spent working on it would be better spent doing
>> something more meaningful and using the money you received to buy a real
>> TDM card or better still, a FXO->SIP ATA.
>>      
> I thought TDM cards were a better solution to connect an IP PBX to a
> landline. Why would you recommend an FXO-SIP ATA instead? And which
> brand/model of ATA is recommended for use with Freeswitch?
>    

Steve


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Re: [Out of curiosity] Why not use a voice modem for FXO?

GillesToo
<quote author="Steve Underwood">Most X100P clones don't use any kind of Silicon Labs chip. Whatever chip they do use will probably not be programmed properly to match the line, because the drivers don't support that. However, with the use of a decent echo canceller you'll probably never notice. Use OSLEC with most X100P cards on most lines around the world and the results should be pretty good.

Thanks for the clarification. I have a bunch of X10xP cards, and they all have chips that say "Si". Unfortunately, the ones that have the supposedly Europe-compatible chip (3014 + 3021)... I couldn't get to work on the computers I have here. I guess it's a hardware issue.

Steve Underwood wrote
The only things those X100P cards can't do, which some more  complex FXO cards can, is detect line current breaks and reversals. Most lines around the world don't produce breaks or reversals so its not a major issue. Everything else is down to what the host software does.
Too bad no one followed the X10xP project and came up with a reliable, entry-level card for SOHO users. $100 is almost the price of the PC on which Freeswitch is running :-)

Thanks for the technical infos.