OK, so here goes the answer:
You have to install de JTapiClient from the plugins page of the Call Manager. From there you can get the JTAPI.JAR file for the version (it's installed in the chosen lib path).
I didn't have that installed on my computer and believed that the JTAPI.JAR file could be somehow directly downloaded from the CUCM.
Dani.
Daniel Mondria:
Hi
I developed an application that uses the JTAPI.JAR 8.5(1.10000) but our Call Managers have been updated to version 8.6.2. How do I get the new JTAPI.JAR for this version so that I can rebuild my app using it?
Dani.