Confused about set-up: PBX + 4 Analog Trunk Lines

OK, I’m new to this, so I may get some things wrong, so bare with me. We’re a small office (around 15 people, give or take). Our current phone system is a small, 13 (?) year old computer running OS/2. As near as I can tell, from my limited education on this topic this past week, we have 4 analog trunk lines coming in and approx. 40 numbers assigned to us (so people can call individual telephones directly). Our current system only has the 4 trunk lines going in (2 physical wires, each with 2 lines) to the old OS/2 box; aside from that it is completely disconnected. I’ve decided to take it upon myself to replace this old server with a new one running Asterisk (already have the server set up with Asterisk installed, though no ATA h/w at all). However, I’m still confused as to how to set this up.

I’m confused as to how the switching works. If a call comes in, how does it get routed to the phone? Is the OS/2 box responsible for routing calls to the appropriate phone? If so, I take it this is done over these 4 lines, which means there is some piece of hardware I have not accounted for (there is a smallish box the size of a small hardcover book we have from Bell that has some lines going into it - labeled S9M). Further, if this is the case, how do I set this up in Asterisk? I keep seeing guides that would use a 24-port FXS to handle the switching which, if the old OS/2 box is currently handling the switching, would seem unnecessary here. Also, I keep seeing set ups for switching based on extensions, though we use direct numbers. I assumed the system handles these too, but I am unsure how to configure this in Asterisk.

The other option here is that this OS/2 box is doing far less than it would seem: no switching, just the auto-attendant for our “main” phone number… Or that the routing is handled else where, but this box can still “see” the calls.

Also, what would you suggest for a 4 port FXO?

Thanks for any help you can give!

Though I hate to answer my own question, I think I just found out we may be using Centrex. That would seem to make sense, which means the OS/2 box is not handling the switching or anything. Though, I am still unsure whether it can see calls coming in at all. It is set up (not by me) with every single person’s “extension” (used internally) and has their names entered and whatnot. Clearly, someone thought it was doing something else other than just handling our main public number/auto-attendant…

Howdy,

For four FXO interfaces, you’d want to look at either the TDM410 (PCI) or the AEX410 (PCI-Express) cards, loaded with four FXO modules, product SKUs 1TDM404BF (software echo cancellation) / 1TDM404EF (DSP echo cancellation) or 1AEX404BF (software echo cancellation) / 1 AEX404EF (DSP echo cancellation).

But, we don’t support DIDs delivered on analog lines.

Are you certain that you’ve been delivered analog circuits?

Also, if your phones aren’t directly wired into that OS/2 box, then that OS/2 box isn’t the one controlling the switching of your phone calls.

What kind of internet connection do you have? Have you thought about using an IP provider for PTSN connectivity?

Definitely have and I think we’ll go that way in the future.

[quote]For four FXO interfaces, you’d want to look at either the TDM410 (PCI) or the AEX410 (PCI-Express) cards, loaded with four FXO modules, product SKUs 1TDM404BF (software echo cancellation) / 1TDM404EF (DSP echo cancellation) or 1AEX404BF (software echo cancellation) / 1 AEX404EF (DSP echo cancellation).

But, we don’t support DIDs delivered on analog lines.

Are you certain that you’ve been delivered analog circuits?

Also, if your phones aren’t directly wired into that OS/2 box, then that OS/2 box isn’t the one controlling the switching of your phone calls.[/quote]

Thanks for the recommendation. I think we’re actually using a centrex to handle the switching, so this box is not doing much, it would seem… I basically have free reign after hours though, so once I get the adapter, I should be able to mess around and see exactly what it is doing.