...and we're on the same carrier too. What's your BES and Exchange version? It may be newer than ours...
I have checked this time and time again, but do not have the issues with the CPU that you all do. It might be your Sec policy that may be tighter than ours and is causing the phone to keep contacting the BES for Sec lookups...I don't know...
See this article - maybe it applies to you
http://www.blackberry.com/btsc/dynam...C&kcId=KB25412
Also - ask the sysadmin if the same thing happens on the BES CPU...VMware was known to sometimes cause these issues in the past