Sounds very much like a problem I've been having in the early days. I'm not sure it's exactly the same but here are a few pointers:
Install the latest phone load (6.0.1sr2).
Trace the HTTP interaction between your 7970 and application server and check the page that the phone gets before the problem ocurrs.. does this xml code contain all the necessary information, especially the QueryString parameters that would contain the action parameters?
I also recall that earlier phone loads had problems with port 8080 (default port for tomcat - the server which I presume you use to run your jsp applications).. I opened a case about this and I think it was fixed. Not passing the conference ID was also something that ocurred on the 7905 but once again I think it has been fixed since (sorry to be vague, that was a long time ago).
Anyway, upgrading phone loads and tracing the HTTP traffic should get you there (imho HTTP tracing is a must unless you run a debugger on the JSP app).