asterisk users - Apr 2004 - Adtran 850 questions

I just wanted to ask about using Adtran boxes to support analog lines
into an Asterisk box.  Right now x101p's are just too sensitive to RF
noise inside the PC.  Going with an external chassis looks like a good,
albeit expensive option.  It looks like I can use the Digium T1 card
into an Adtran 850.  The Adtran 850 would need FXO cards.  It would also
need the echo cancellation module.  Is this correct?
	What other options are out there with hardware level echo cancellation?

			...Jeff