Replacing old PBX - how to connect to T1?

I’m setting up a new install and replacing an old Nortel PBX. Being new in this arena, I am unfamiliar with what will be necessary to connect to the existing T1.

The current environment has a Cisco IAD2432 (specifically IAD2432-24FXS, if that helps). There is a 25-pair Amphenol connector on the back that is punched down to 66-blocks, providing analog lines to the old PBX. Additionally, there are two RJ-45 cables that plug into ports “T1/E1 1/1” and “T1/E1 1/0”. Finally, there is an RJ-45 plugged into FE0/0 connecting to the firewall for Internet.

So - here’s my confusion. How do get those T1 lines talking to Asterisk? The Cisco is provided by the phone vendor, and most likely not an option for me to configure.
I assume that I’ll ditch the 25-pair wire. Does the Cisco HAVE to be reconfigured? What type of board do I need (if any) to install in the Asterisk server?

For the sake of providing too much detail, rather than not enough, I can tell you that this environment currently has about 10 phone lines and 30 extensions. While most of the phone lines are punched for the use of the PBX, there are a couple that are reserved for “analog” services - such as elevator phone, fax machine, and fire/security system. I will need to continue to provide these POTS lines for security sake, and would rather not have to use ATA’s to convert VoIP to analog.

Hopefully I have provided enough detail. In summary, the questions I have are:

  • Will the Cisco have to be reconfigured?
  • What PCI card (if any) do I need in the Asterisk server?
  • For the PCI card - what configuration of FXS/FXO ports are needed? This is still confusing to me.

Thank you in advance for your help!

Hi Michael,

What I understand from your post is that you intend to keep the current phones setup and only replace the PBX, meaning you’d continue to use the analog phones you already have. If this is the case, you’re gonna need to keep the Cisco IAD and reconfigure it. For the T1 lines you’re gonna need a card like these: (just checked: 24 port FXS card would cost you about $2k). My suggestion is not to cheap out on such cards and get an echo cancellation module with them.


Sorry if I wasn’t clear. The PBX -and phones- are being removed. Asterisk will be installed as well as new SIP phones.
My question is specifically how to handle the phone lines. It’s simple if it is a SIP trunk or POTS lines, but with a T1 -> IAD I’m not sure how to get the dialtone to the Asterisk.

You said the IAD is FXS modification, meaning it provides ports for the phones. You won’t need it if you’re gonna use SIP phones.