Apparently Alltel is requiring the X-Alltel-MDN registry value now ("originator address not found" anyone?), on top of that, ArcSoft 5.2.8.45 deletes it on send! Despite its necessity to send successfully! I rolled everything into an Alltel flavored version of Ryan Mogul's original cab, including a MMSTransport.dll I patched to quit deleting the Alltel value.
Check the updated first post.