[kwlug-disc] Unlimitel/ATA pricing

L.D. Paniak ldpaniak at fourpisolutions.com
Thu Mar 12 08:57:52 EDT 2009

Hash: SHA1

Paul Nijjar wrote:

> Let me see if I understand.
> Say I have 8 Bell Lines already going into my Nortel PBX, and that I
> have the expansion capacity to add more incoming lines. Here's the
> diagram:
> 8 x Bell lines -> CICS -> Extensions -> Digital Phones
> Now I get one of those Linksys SPA-2102 boxes that Lori used in his
> demo. This is an ATA with two FXS ports. I order one DID from
> Unlimitel. To avoid NAT problems I stick the ATA in between the cable
> modem (or DSL modem) and my firewall. 
Each FXS port on the 2102 has to register to its *own* DID.  You cannot
do one DID to two independent extensions with the 2102.  This is already
PBX-land.  The minimal way to do that is use a SPA9000 which is a souped
up router acting as a PBX (a production version of an Asterisk-hacked

> Next I hook up the two ports of the ATA to my Nortel CICS. The CICS
> should now think that it has 10 incoming lines, and furthermore it
> should think that all 10 lines are plain old telephone lines. Now the
> diagram looks like this:
> 8 x Bell lines -----------------> CICS -> Extensions -> Digital Phones
> 				   ^
> Unlimitel -> Internet -> ATA ------|
>>From what I have been reading in this thread, this should be all I
> need, right? The ATA will do the conversion from Unlimitel's packets
> to analog phone signals that the CICS can understand. 
If CICS handles plain old phone lines, then this should work except you
have only one extra line from VOIP and the 2102 (per DID).

> I'm also thinking that the SPA-3102 is actually worse for me in this
> setup, because it has one FXS and one FXO port, and the FXO port does
> not do me any good in this setup. Furthermore I am believing that
> because this ATA has two FXS ports, I can use both of them
> independently with the CICS even though they share a DID. 

They can be used independently, but they do not share a DID.

> As far as I can tell I don't have to set up Asterisk or softphones or
> anything else to make this work. And because the CICS sees the lines
> from the ATA as incoming telephone lines, the only phone wiring I have
> to change is to punch in the lines from the ATA to my CICS. 
> Assuming I am happy with this not very open-sourcey setup, am I
> understanding the situation correctly? What am I missing?
> I guess the catch of this system (or VoIP in general) is that my
> Internet bandwidth usage will go up, so if I don't have uncapped
> internet I have to start to worry about overrunning my bandwidth
> between phone usage and long e-mails to the KWLUG list. 
> - Paul

I suggest running the ATA on a separate line (your own phone) before you
unleash VOIP on your PBX users.  Though there will probably be no
hangups (so to speak), you want to make sure that the bugs are worked
out before people in the office start using VOIP.  People expect Bell
quality telephony when they pick up the phone and anything is just
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