[Asterisk-Users] Digital Phones

[Anton Krall]

Guys.. I have a question, maybe it's a simple one, maybe not but its
puzzling me..

Avaya, Nortel, etc. use digital phones (are they ADSI?) on their PBX's. How
can Asterisk take advantage of these phones? 

For analog, you cn use FXS, but what do you use for this phones? How can you
take advantage or current infraestructure without the need to replace all
phones?