If you have installed BESX and can not get your blackberries to connect OTA then it is a problem with the BESX not finding the server name. You must edit the registries for BESX to point to the server name. Please see this post. As soon as I did this I activated 5 blackberries on my server OTA all on BIS accounts. No issues after this.
I've been banging my head against the wall for days trying to get my 8310 on a BIS plan to activate. Every attempt at a wired activation resulted in utter failure. I added the 001e6602 entry to the registry, restarted dispatcher, and success.
So, for the record, you can absolutely OTA a BB w/BIS only.
That's the only problem I had. I activated 5 blackberries all of which are on BIS accounts through Verizon. I did read on bbleaks.com though that Verizon is going to make you upgrade to a 44.99 plan but right now I have all 5 activated and running off of my BESX and exchange 2007 server.