[Asterisk-Users] Three (quick?) questions...

[Lyle Giese]

Paul is right.  For voice, there are two varities of T1's.  The straight
channelized T1 provides 24 pots lines and no custom services, like caller
ID.  The other is a PRI ISDN, which is 23 voice and 1 'D' channel.  The
telco can now provide more services, including caller id over the D channel,
backup routing of voice calls when the T1 goes down, and outbound caller id
of the extension placing the call for E911 translation.

Traditionally splitting a T1 for voice and data used a special CSU/DSU that
you can program to provide two T1 streams and divided the channels between
the PBX and the router.  It's very easy to configure a CSU/DSU for this.
The voice stream is usually a T1 data stream that connects to the PBX with
the data piece sent via v.35 serial to the data router.  Most of the
installs I have seen were ISDN type voice, so chan 24 was always reserved
for the D chan signalling.

I think these CSU/DSU's run between $2,000 & $3,000 new(I have not priced
them for a while), but are quite easy to configure and install.

I am new to this forum, but worked for 23 years for the telco here doing the
central office piece of this puzzle and then for 5 years doing new office
turnups for a wireless telco where we put in many split T1's using Adtran
CSU/DSU's to split the data stream.

Lyle

----- Original Message ----- 
From: "Dean Collins" <dean at collins.net.pr>
To: <asterisk-users at lists.digium.com>
Sent: Saturday, July 10, 2004 11:52 PM
Subject: RE: [Asterisk-Users] Three (quick?) questions...


Hi Paul, you would know better than I would but I always thought a T1
was 24 channels of voice with the signalling additional like we have in
Australia a Pri or E1 is 30 channels voice channels plus signalling.

Can anyone else clarify?

Cheers,
Dean


-----Original Message-----
From: asterisk-users-admin at lists.digium.com
[mailto:asterisk-users-admin at lists.digium.com] On Behalf Of Paul Mahler
Sent: Sunday, 11 July 2004 2:39 PM
To: asterisk-users at lists.digium.com
Subject: RE: [Asterisk-Users] Three (quick?) questions...

Hi,

T1 is the carrier. T1 provides 24 "D" channels of 64Kbps each.

Telephone companies provide ISDN (integrated services data network) on
top
of T-carrier. Two common flavors are BRI (basic rate interface) and PRI
(Primary rate interface.) BRI provides two 64 kps channels, PRI provides
23
usable channels, the 24th is used for signalling.

So--you can get phone calls over a T1 or over a T1 that is provisioned
as a
PRI. You can get 24 calls on a T1 and 23 on a PRI.

A T1 has 24 channels. You can split, that is partialize, the channels
between data and voice. You can do this with hardware outside the *
server.
Higher end Cisco routers, for example, support this.

You can also use * and linux to partialize the T1. You better plan on
spending a lot of time on making it work if you do it this way. You have
to
install the Linux packages to split the line. NON trival. Works great,
though. Much less expensive, too.

Paul


Paul Mahler
pmahler at signate.com
Signate, LLC
665 Third Street
Suite 100
San Francisco, CA
 94107-1901

 Asterisk Services and Training









> -----Original Message-----
> From: asterisk-users-admin at lists.digium.com
> [mailto:asterisk-users-admin at lists.digium.com] On Behalf Of
> Ken D'Ambrosio
> Sent: Saturday, July 10, 2004 8:33 AM
> To: asterisk-users at lists.digium.com
> Cc: kend at xanoptix.com
> Subject: [Asterisk-Users] Three (quick?) questions...
>
> [Please excuse if this is a repeat; I initially tried to send
> it from a different account, and it's been held up for a
> couple of days awaiting moderation.]
>
> 1) What's the absolute minimum required (hardware-wise) in
> order to get one
>    in-bound POTS line into Asterisk, and then have IP phones "inside?"
>    [In other words, I obviously need a NIC -- but what would be the
>    bare-bones telco POTS interface?]
>
> 2) What phones would be recommended for inexpensive (doesn't
> even need LCD),
>    and yet functional?
>
> 3) In order to share data and voice over a T1, does it have to be PRI?
>    [I've got a T1 I could probably play with, but I'd like to be sure
>    it'll... well, you know: work.]
>
> Thanks,
>
> Ken D'Ambrosio
> Sr. SysAdmin,
> Xanoptix, Inc.
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