On Oct 20, 2005, at 2:36 PM, Michaël Gaudette wrote:
Tom, Thank you! This was all hypothetical, because I'm trying to
wrap my mind around the concept. But you've made it much clearer
for me. I still have a few follow-up questions...
1a) Forget the hypothetical company now. Let's say 6 outside lines
were deemed sufficient, and there were 12 employee (i.e. inside
lines). Could I have the same Digium T1 card to service out and
inside the company?
Yes, you could, but you will have to compare the costs of a
fractional PRI or T1 with the costs of 6 regular copper POTS lines
and the equipment needed to interface them with Asterisk. POTS lines
might be cheaper, but you will need:
1.) 2 Digium TDM400p cards with FXO modules. These cards seem to be
finicky, especially more than one, so you might want to stay away.
2.) Multi-port FXO gateway. VOIPSupply might be able to point you to
some decent models
3.) T1 Card and a Channel bank with FXO Modules. You could even buy a
channel bank that has 12+ FXS modules for the analog extensions and 6
+ FXO ports for the incoming lines.
1b) I'm fairly certain of this, but anything going outside, I could
use the same T1 for receiving calls as for sending them, right?
(not with the same channel at the same time, obviously, but I could
use 2 lines incoming and 4 outgoing, or 3 incoming and 3 outgoing,
depending on the current situation, without reconfigurin the PBX?)
Yes. As mentioned by someone else, use the group functionality of
Zaptel to let Asterisk select the next available channel
2) When you say a PRI is necessary for a Caller-ID name (as opposed
to just number), I've looked around and I understand a PRI uses a
T1 tunnel (24 channels) but a bit more expensive. Is this a fact,
or is it something completely separate that I couldn't use with
Asterisk? Or am I completely out in left field?
A PRI uses a T1 loop, but you can only send voice or data using 23
channels because the 24th channel is the D channel and is used for
signalling. Our PRI was actually cheaper than what we were paying for
our T1, but that might simply be due to the volume we sent over the
line. Check with your provider.
[snip]
Yes, but you could use a Sangoma card, too.
Will definitely take a look and compare. Any pros and cons I
should know that isn't obvious from their documentation?
Well, Digium's latest firmware release seems to have made major
improvements to their cards. However, the Sangomas are great cards as
well, but they do require an additional driver, whereas Digium cards
work without anything other than Zaptel. Digium's may do this as
well, but I know that the Sangomas are capable of handling the D-
channel signalling of a PRI directly on the card so that Zaptel
doesn't have to do that.
- Something (not sure what) on the outside to connect to those 72
phones (3 T1 cards internally connecting to a wire panel, in turn
connected to 60 phones?
3.) Analog phones connected to a Channel bank, connected to a T1
card.
Thanks. I already knew about SIP and IAX, since I'm more of a
computer geek than a telecom one that part means more to me :-)
Channel bank is what I meant.
Keep in mind that you will not need a channel bank if you are using
SIP or IAX.
For something like this as your first serious production install, you
might want to consider hiring a consultant.
I'll certainly consider that when (I should say if) a real project
does require me to do so.
Give me a call at that time, then!
Thanks alot Tom, it makes me feel more secure in considering
Asterisk for jobs like this when there are helpful people like you
around.
It's who I am; it's what I do!
Tom
------------------------------------
Tom Rymes
Cascade Link Systems
www.cascadelinksystems.com
(603) 375-1414
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