I don't think that there is a JTAPI implementation that supports the Telekom Octopus directly. You can try JTAPI over TAPI with the gjtapi (on sourceforge).
The standard API documetation of the JTAPI can be found at the Java Comunity Process (jcp.org).
This documentation contains some sample code in the package description of javax.telephony.
Monitor/Track calls is quite easy :
- Connect to you Phone system (details depend on the implementation), this will result in a Connection
- Get the Extension you want to observe : Connection.getTerminal or Connection.getAddress
- Implement CallObserver or CallListener
- Now you can add your CallObserver or CallListener : e.g. Address.addCallObserver.
In the eventhandling routines e.g. CallObserver.callCahngedEvent(CallEv ev[]) you can get all relevant information out of the event Object and do whatever you want with it.
That's all ...
Observer Listener?
Depending on your JTAPI implementation Observer may be deprecated or not.