[Asterisk-Users] T1 Hardware Echo Can

[Andrew Kohlsmith]

On Saturday 10 July 2004 11:21, Rich Adamson wrote:
> If you install a T1 card and an external T1 mux (with fxo cards), the
> echo can function already exists within the mux and/or cards. Don't
> really need 'another' external echo can box unless you actually
> purchased a T1 mux that didn't have echo can in the first place (and
> they do exist).

As Steve already said, generally speaking echo cancellation hardware on T1/E1 
interfaces is an option adder.  If it doesn't mention it, it doesn't have it.

> If you install a PRI (or related types of channelized T1 arrangements),
> you don't need an external echo can function as those interfaces are
> generally 4-wire to 4-wire interfaces already. If echo exists, its
> generally the result of other interfaces (located somewhere else) and
> those locations should be addressing the corrective actions needed to
> resolve the issue.

You will often hear echo from the far-end hybrid, even on PRI, as I have found 
out.  Normal KSU/PBX systems with T1/PRI interfaces have echo cancellation 
hardware within the KSU itself.  I am purchasing a T1 echo canceller in order 
to try and eliminate the echo we hear (i.e. far-end echo) -- something I 
didn't think I'd need to do.  Our telco (Bell Canada) seems oblivious to any 
knowlege about echo cancellation for T1 within the CO, but I continue to 
press, because every now and again you hear a glimpse of "oh yeah we can do 
that, your line just wasn't engineered with that equipment" kind of 
blurb.  :-)

-A.