[Asterisk-Users] ISDN Hardware

[Jeff Lists]

I have a test install set up as follows

Grandstream 102 ---- Asterisk ---- X100P ---- Adtran Express 3000 ---
ISDN line to PSTN

Most things I want to do work fine except I do have some intermittent
problems with an echo.  I am assuming that this is created in the link
between the X100P and the Adtran terminal adaptor.

I am not sure of the proper terms but on the PSTN side of the Adtran
there is one pair of wires which carry two channels.  On the interior
side of the Adtran there are two pairs of wires which each carry one
channel (is this a BRI channel??).

In the final install I will be replacing the X100P with some type of
ISDN card.  I currently have three ISDN pairs which create six lines. 
I would like to get enough hardware to be able to add one more pair of
lines soon.

My question is what type of ISDN card do I need?
Will this replace the Adtran or plug into it?
Since this is all digital is it a safe assumption that my echo
problems will be gone?

Thanks,
Jeff