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Posted by John Doe on April 30, 2006, 9:50 pm
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Hi
I browsed through the archives, but didn't find a very good
explanation as to why we can't use a good voice modem as FXO card for
small setups (read: cheap).
Is it because their CODECs suck, or they don't support enough of them?
Thanks.
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Posted by Enzo Michelangeli on May 1, 2006, 3:27 am
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----- Original Message -----
> Hi
>
> I browsed through the archives, but didn't find a very good
> explanation as to why we can't use a good voice modem as FXO card
> for small setups (read: cheap).
>
> Is it because their CODECs suck, or they don't support enough of them?
As far as I know, most (all?) voice modems are half-duplex: they can send
or receive voice, but can't do both things at the same time. Moreover,
their codecs are usually based on some variant of ADPCM, and the driver
should transcode the data into some other format suitable for VoIP. All in
all, it's just not worth the trouble.
On the other hand, some Winmodems (or Linmodems, if we prefer a
Penguinically-correct designation ;-) ), i.e. data modems where the data
modulation/demodulation is offloaded to the CPU, can be adapted as FXO
cards just rewriting their software drivers. This is not trivial
(requiring the knowledge of the specific hardware) but was done by Digium
for two models, one based on a Motorola chipset and another on an Intel
chipset. They used to be sold under the names "x100p" and "x101p"
respectively. Digium has now discontinued them, but there are still
several third-party vendors of compatible hardware: just check the hits at
http://www.google.com.hk/search?q=x100p .
See also: http://www.voip-info.org/tiki-index.php?page=X100P+clone
Enzo
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Posted by John Doe on May 1, 2006, 3:40 am
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(snip)
Thanks for the links. I'm about to order a couple of those X10?p cards
for my first test Asterisk setup, and see how they fare.
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Posted by Raqueeb Hassan on May 1, 2006, 1:28 pm
If you were Registered and logged in, you could reply and use other advanced thread options > See also: http://www.voip-info.org/tiki-index.php?page=X100P+clone
IMHO, most clones can't display the incoming call's callerID.
--
Raqueeb Hassan
Bangladesh
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Posted by John Doe on May 1, 2006, 2:29 pm
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>IMHO, most clones can't display the incoming call's callerID.
Uh-oh... That's an important feature :-/
Does someone know about real clones as advertised on eBay
(http://search.ebay.com/fxo-asterisk), such as...
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=9719116318
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=9718408471
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=9720092845
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=9718298351
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=9718788040
Thank you.
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