As far as you know. Now consider that the FBI statements about what evidence they gathered from San Bernardino (evidence which is largely not part of a criminal

As far as you know. Now consider that the FBI statements about what evidence they gathered from San Bernardino (evidence which is largely not part of a criminal prosecution so not subject to defense discovery) as part of a vector of information which the FBI might choose to manipulate to better enable their ability to exploit the intelligence they have. So what do you really know about work phones and burner phones?