[asterisk-users] PRI Card

[Jared Smith]

On Thu, 2007-07-19 at 12:11 -0400, mail-lists wrote:
> thanks for your reply - Our setup isn't complicated at all - just a PRI 
> coming into an asterisk box. Maybe you could answer another question for 
> me - what disadvantages does a PRI have from a channelized T1? or vice 
> versa.

A channelized T1 is 24 channels over a T1 -- basically little more than
24 POTS lines that happen to come across a 2-pair digital interface
rather than 24 pair analog interface.  PRI over T1, on the other hand,
only gives you 23 voice channels (often call B or Bearer channels), and
uses the 24th channel for call signalling between you and the upstream
switch.  (This channel is called a D or Delta channel and I've even
heard it called a Data channel, although my friends in big telco say
that the D doesn't stand for Data.)  PRI gives you much more advanced
call control, allows you to more easily do things like DIDs, and gives
much quicker call setup and dialing.  Depending on your location, the
only major downside to PRI might be price... they're often more
expensive than channelized T1s.

> 
> is the TE205 the double port version of the TE120P?

Yes, the TE205P is the 2-port version of the TE120P.  Once you get to
the 2-port versions and 4-port versions of the Digium cards, they come
in three flavors: a card for 5-volt PCI slots (the TE205P, for example),
a card for 3.3-volt PCI slots (the TE210P, for example), and a card for
a PCI-Express slot (the TE220P).

> Also, what's required as far as echo cancellation goes? Is that built 
> into these cards or do you have to move up to a TE207P?

It depends... if you're OK with software echo cancellation, you don't
need anything special.  If you want the hardware echo cancellation
(which many people do), you could move to the TE207P or TE212P cards
(for PCI slots in 5v and 3.3v, respectively), or the TE220P plus a
VPMOCT064 echo cancellation module.

> What is the difference between a TE205 and a TE210?

Explained above... difference between the different types of PCI slots.

> Sorry about all the qeustions - the info on digiums web site doesn't 
> really make this clear.

I agree. Luckily, I know Digium's marketing department is working to
improve the information on the website so that it's clearer which
hardware is appropriate for different situations.

-- 
Jared Smith
Community Relations Manager
Digium, Inc.