Considering that BO and the average "news" reporter know squat about technology, it's possible that the phone number for his personal phone was ported/moved to the network/carrier used by the govt. and a new SIM card was put into his phone. So, that to BO it seemed like the same phone, but it was now part of the high security network. Just thinking out loud ...
I guess it could happen like that.
Although didn't Barry tell us that he knows more about everything than anyone else? Could that have been a fib?
;-)