I am new to jtapi  too,but Apache has implementation  of JTAPI.its name is Asterisk JTAPI.
it sounds that Asterisk is easy too use,but i don't have any experience with Asterisk in real world application.for more information please see http://asterisk-jtapi.sourceforge.net/.

I would be glad if you can share  your experience about ibm's implementation with me.