asterisk users - Apr 2004 - Toshiba Digital Phones -> Asterisk

I am planning an * install at my business.  It will be replacing an
existing Toshiba system (I think it is a 424dk).  I was wondering if
anyone knows of a way for me to use my existing Toshiba phones to
connect to *.  I would rather not have to spend the $15,000 to replace
all of my phones, but I can't find any other way to do it.  Your help is
greatly appreciated.

Thanks,

Robert Jackson