I tried 184.108.40.206 for my problem and it didnt work. The BES thinks the Software Configuration I have created for the Lotus Instant Messaging has been sent to the Device but on the Device there are none of the Modules/Service Books for the application.
I had to use the Blackberry Desktop Manager Apploader to get the Instant Messaging onto the 8120.
I did a test push to an old 7130 and that worked fine using wireless. So there is something about this 8120 and/or its software revision.