Brian points out that the government claims it will only tap international calls.
Then he reminds you of the last time you dialed an 800-number for customer service and ended up speaking to Vhopal, India.
Say you have a situation with John Druglord is in Arizona making a phone call to Joe Drugdealer in Sacremento. They plan on coordinating a distribution of a large number of goods. The feds want to catch these two and make a big drug bust.
Now, if they wanted to, the feds could tell the telecom company to reroute all of John Druglord's phone calls to a server overseas, and re route them back into the US on it's way to Joe Drugdealer's phone. It would take literally milliseconds. On the way back into the country, the feds would have the legal ability to tap the phone conversation between two US citizens that are within the country.
Of course, John Druglord could also be Sally Greenpeace, Bill the John Bircher, or somebody running a 527 who is critical of Barack Obama.
Good thinking, Brian. Now you've depressed me for the rest of the day.