Which TDM8XX PCI analog card should I choose?

Hello guys,

I am new here and am not very technical. I want to link my internal IP phones (I am using Cisco’s Linksys IP phones) with the public phone lines (aka the landlines).

Now I am told I will need a so called “DIGIUM 8-port FXO card” as an interface btn the incoming landline and my internal IP phones.

Coming to digium website I found 5 products which answer to the decription of “DIGIUM 8-port FXO card”.

The products are listed at store.digium.com/products.php?category_id=37

Now all five products are similar except for 3 additional components namely:

  1. Quad Station (FXS) Module
  2. Quad Trunk (FXO) Module
  3. 128ms Hardware Echo Cancellation Module

Now I am not a technical person so I don’t quite understand what these three modules are supposed to do. (ie, what value do they add, and whether they are absolutely necesary).

So tell me, how do I choose from these FIVE available options?


You need one FXO port for each simultaneous call you want to have with the outside world.

The modules listed below for the TDM8XX Card (max 8 ports) are 4 ports per module and you can have up to two modules per card.

If you need 4 or less FXO ports you can also get a TDM4XX card (max 4 ports) card that allows you to buy a one port module and up to 4 modules per card.

If you only need 4 now but may need more in the furture I would strongly suggest you get the 8 port card as running multiple cards in a system can cause issues.

If you need more than 8 FXO ports you might want to look into getting a partial or full T1 as the price is usually less but you would need to do some price comparisons in your area to find the sweet spot.

Thanks Swaterhouse for clarifying.

Have one more question though. What is the difference between TDM8XX and AEX800 cards?

The TDM fits in a PCI slot and the AEX fits in a PCI-Express slot. If your server has a PCI-Express slot the AEX would be a better choice.