Broadvoice with Cisco 7970 and Spa-2000 both randomly unregister/re-register

[pcbastard]

I have 2 voip phones connnected to my 8.10 installation.  One is a 7970 and the other phone is connected to an SPA-2000.  Both phone work for incoming and outgoing calls through a Broadvoice BYOD account.  But, after some time, both will become un-registered.  I get the message "The device you are using is not registered...".  If I reboot, or wait some more time, it may come back to life.  I can always make calls between the 2 phones. 

Perhaps I am not allowed to have 2 registered devices with my basic Broadvoice account?  Do I need to pay more to have multiple phones even if ony one is ever being used at one time?

Thanks for any help.

Leo