I don't. PRISM doesn't work how you described it, as far as I know... It is basically a backdoor to Apple for the NSA (so whatever Apple can see, the NSA can also see).
PRISM doesn't work the way you've described it. It ingests data from the FBI's Data Intercept Technology Unit, which handles court ordered wiretaps on individual accounts from Internet communications services. You can see this in the slide Snowden leaked.
http://www.washingtonpost.com/wp-srv/special/politics/prism-...
https://medium.com/@alecmuffett/how-to-talk-about-prism-and-...