[Asterisk-Users] EC needed in all-digital situation?

[Warren]

Andrew Kohlsmith wrote:

>On Thursday 15 June 2006 10:22, Warren wrote:
>  
>
>>I was just told that for my forthcoming system I will be getting a data
>>T-1 instead of a voice T-1.  Given that all of the handsets will be voip
>>phones, no analog at all, do I need echo cancellation?  I looked at the
>>voip-info wiki and it seems to me that the answer should be "no" but I
>>would like to confirm that.
>>    
>>
>
>All-digital setups do not *generate* echo since there is no hybrid circuit to 
>reflect energy.  However all-digital systems can still have echo if the 
>far-side is a 2-wire system and the latency is sufficiently high.  (Anything 
>with a PCI bus can bring this latency up easily.)
>
>Also, if you have an ueber-cheap phone which acoustically couples the speaker 
>in the handset with the mic you can introduce echo on your all-digital system 
>that way.  The same goes for cheap speakerphones and/or acoustically "hard" 
>rooms.
>
>-A.
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So the next question becomes...  Is hardware EC necessary or can *
handle it in software?  I am looking at some pretty beefy hardware for
my platform, a Dell PE2850 with dual Xeon 3Ghz processors and plenty of
RAM to spare.  I am likely starting with a single T-1 PRI line and
expending to 2 within a year, but that would be the max.  I am not sure
of how many simultaneous calls that would be, but let's assume I want to
use a b-channel's worth of bandwidth for each, so 23 max to begin with.

Can * do software echo cancellation for 23 (and eventually 46) calls on
a dual Xeon 3.0Ghz system?

W
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