ATT Truevoice?

ATT Truevoice?

Post by Frank Heisl » Tue, 02 May 1995 04:00:00



I was wondering....I'm up in Canada - and don't have the ability to test
this, but I was wondering if anyone has ever tried making a long distance
28.8kbps connection over AT&T Truevoice lines?  How does this 'treatment'
affect the connection?

Anyone try this?

--
Cheeri'o...
           Frank...

 
 
 

ATT Truevoice?

Post by bu.. » Wed, 03 May 1995 04:00:00



> I was wondering....I'm up in Canada - and don't have the ability to test
> this, but I was wondering if anyone has ever tried making a long distance
> 28.8kbps connection over AT&T Truevoice lines?  How does this        
>'treatment'  affect the connection?

It doesn't.  The AT&T "Truevoice" treatment is incorporated into the echo
cancellers which are automatically switched out during modem data calls.

It's completely a NON-ISSUE.

std. dosclaimers apply.  I do not represent my employer in this forum.

 
 
 

ATT Truevoice?

Post by Dan Moo » Wed, 03 May 1995 04:00:00



>I was wondering....I'm up in Canada - and don't have the ability to test
>this, but I was wondering if anyone has ever tried making a long distance
>28.8kbps connection over AT&T Truevoice lines?  How does this 'treatment'
>affect the connection?

        TrueVoice is basicly a putting an equalizer in the telephone circuit,
just like the one you have on your home stereo.   This is bad (very, very bad)
for higher speed protocols such as V.34.

        The ANSam tone transmitted by the answering V.34 modem
contains phase reversals every 450ms.  These phase reversals tell the
telephone network equipment to disable any echo cancelers in the circuit.  On
lines with TrueVoice they are also supposed to disable the equalization, so
having TrueVoice on a line shouldn't bother V.34 calls.

        At this time I have heard conflicting reports on whether or not the
TrueVoice equalization is actually being disconnected when phase reversals are
detected in the ANSam tone.  

--
Dan Moore
Supra Corporation

 
 
 

ATT Truevoice?

Post by Ed Ha » Wed, 03 May 1995 04:00:00


: I was wondering....I'm up in Canada - and don't have the ability to test
: this, but I was wondering if anyone has ever tried making a long distance
: 28.8kbps connection over AT&T Truevoice lines?  How does this 'treatment'
: affect the connection?

It makes no difference that I've been able to notice.  AT&T claims that
it is automatically disabled during modem calls.

                -Ed Hall

 
 
 

ATT Truevoice?

Post by Ed Ha » Sun, 07 May 1995 04:00:00



: : It makes no difference that I've been able to notice.  AT&T claims that
: : it is automatically disabled during modem calls.

: Hmm...how would AT&T know the difference between a long distance modem
: call and long distance voice call?

Well, if you managed to scream or whistle into your phone in such a way
as it sounded like a modem, you'd find out.  Really, the echo
suppressors used in long-distance circuits have to be turned off for
modem calls, so they are set up to recognize a modem's answer tone and
shut down.  There are even standards as to just what is to be recognized
as such a tone in terms of frequency, timing, and so forth.

So all AT&T needs to do is shut off TrueVoice(tm) along with echo
suppression.  What could be easier, given that the facility is already
there?

                -Ed Hall

 
 
 

ATT Truevoice?

Post by Frank Heisl » Sun, 07 May 1995 04:00:00


: It makes no difference that I've been able to notice.  AT&T claims that
: it is automatically disabled during modem calls.

Hmm...how would AT&T know the difference between a long distance modem
call and long distance voice call?  From what I have seen, AT&T Truevoice
boosts the lower/mid registers (moreso lower).......

Nonetheless, it is interesting.....

--
Cheeri'o...
           Frank...

 
 
 

ATT Truevoice?

Post by Christian Weisgerb » Mon, 08 May 1995 04:00:00



> Hmm...how would AT&T know the difference between a long distance modem
> call and long distance voice call?

Have you ever listened to a pair of modems connecting? The answering
modem outputs a 2100Hz tone (some old American ones use 2225Hz) which is
intended to disable certain aspects of the phone network that interfere
with modem operations.

--

 "Sei froh, dass ich es nicht in SNOBOL geschrieben habe." --Chr.Haller

 
 
 

1. ATT Truevoice

Someone mentioned their impressions of Truevoice.  Lows boosted and
overall volumne increased.

Is not bandwidth needed to transmit a signal related to the bandwidth
of the information in that signal.  And if they reduce the highs, and
the bandwidth requirements, does not let them get more voice channels
into a given digital transmition channel?  Is not this marketing
getting people ready for the distorted sound quality as this carrier
crams more voices on a wire?  Will not high speed modems have trouble
with this distored channel, switch to slower speeds automaticaly and
maybe unknown to the user, and spend more time connected to get their
data through?  Am I too cynical?

Ken Thompson    N0ITL
Disk Array Hardware Development
Peripheral Products Division
NCR Corp.  an AT&T company  
3718 N. Rock Road  Wichita,Ks 67226
(316) 636-8783  

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