[help]qustion about the hardware of the interface

I am planning to change the old system.
The new system looks like so:
1.pstn through 8 isdn connect with *box
2.all phones are ip phones and connect to *box
3.4 fax connect to *box
my question is , what kind of interface cards should i take as interface.

voiptalk.org/products/Eicon+ … M+PCI+Card

digium.com/index.php?menu=pr … ct=TDM400P

voip-info.org/wiki/view/Analog+T … e+Adapters

voip-info.org/wiki/view/Aste … +Telephony