I think I may know what the problem was. I had sent Norm a cut&paste of my formerly working config. Norm says that my SIP from invite header said NPAN@NPAN rather than NPAN@codeblue.voipo.com. I just looked at my config, and somehow I had set fromdomain=codeblue.voipo.com to fromdomain@NPAN, which would explain things. I can't confirm this until I get home, but danielc, you may want to make sure (if not already) that you have your config set up per the knowledgebase article:

http://support.voipo.com/index.php?_...&kbarticleid=2