Tim, Thanks for your suggestion. JBMESSAGING-1220 (together with JBREM-765) does indeed answer my question about the meaning of and the difference between timeout and callbackTimeout. But unfortunately, it does not seem to match our problem. The callbackTimeout of 10 sec has been introduced in JBM 1.4.0.SP3_CP02 and we were already testing with JBM 1.4.0.SP3_CP03 anyway. The callbackTimeout obviously does not take effect in our scenario. Thanks, Ralf Torsten View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4194087#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...