as someone that has created voip systems, i can tell you the audio can be stored @ about 20 kbps (and that would include encryption). the audio quality would be perfectly fine for conversational understanding (careful not to say ‘perfect’)
so the question of storage comes down to... how many minutes do Americans talk on the phone every year? this will lead you to the answer for whether or not it’s easily stored. at first blush, i’d say it’d be no problem if they designed it properly.
indexing it so you can properly pull up all the data related to a person of interest is then key. applying voice recognition to allow for the audio to be ‘parsed’ is also doable. this allows for a call to be flagged in real time and routed to the proper person
the show ‘person of interest’ only gets far fetched when ‘the machine’ starts thinking on its own. otherwise, all the data collection and references into the past is completely possible if not available today
i’m waiting for the day it’s allowed in courts... at which point a judge would bring up your calls over the passed 10 years and point out some behavior from a call years ago to hold against you.
See link in 22. 3 billion phone calls per day or almost 35 thousand per second.
Average length of phone call is 3 minutes according to this:
http://adraughtofvintage.com/2012/05/07/average-length-of-local-cell-phone-call-in-2003-was-3-min-in-2010-its-1-min-47-sec/
Just playing around.... So we have 35K calls per second * 3 minutes per call on an average is 105K Minutes of recording per second.
16.4kb per minute of storage * 105K minutes = 1,722,000kb per second (9.5GB per second)
9.5GB per second * 60 seconds per minute = 570GB per minute * 60 minutes per hour = 34 TB/Hour (rounded)
= 816 TB per day
= 25K TB per month
= 293K TB per year
It sounds like a lot but it isn’t as bad as I first thought.
IBM already has a 120 Petabyte drive that is public.
http://www.technologyreview.com/news/425237/ibm-builds-biggest-data-drive-ever/
So under 300 of those drives for a year’s conversations.