Companies would need to install back-doors on user's machine directly to divert copy of a stream of a audio, get fined or end up moving overseas.
None of the big companies with statements (denials) about PRISM say anything about protecting data that flows through its networking equipment, only that they do not provide access to "stored" data on "servers" (without a warrant).
Here's how to configure a Cisco 7600's LI (Lawful Intercept) "feature":
* Note the cute assumption in the naming of this "feature" - it almost implies that the use of "Lawful Intercept" is necessarily lawful as the feature itself has the word "lawful" right there in the name!
Client to server is just too easy for large organisations to abuse.
Any ISP-grade gear will have this function.
This (knowing the NSA/CIA can and may actually listen to, record, and data-mine ALL electronically mediated communications) has been the default condition since the late 90's when CALEA came about.
'Carriers are permitted to meet their CALEA obligations through the services of “Trusted Third Parties (TTP)” -- that is, they can hire outside companies, which meet security requirements outlined in CALEA, to perform all of the required functions.'