Score one for sanity. Apparently the FBI believed that while eavesdropping on the audio of a conversation required a warrant, capturing any DTMF transmissions sent during the call did not. From the CNet report:
Just about everyone knows that the FBI must obtain a formal wiretap order from a judge to listen in on your phone calls legally. But the U.S. Department of Justice believes that police don’t need one if they want to eavesdrop on what touch tones you press during the call.
Those touch tones can be innocuous (“press 0 for an operator”). Or they can include personal information including bank account numbers, passwords, prescription identification numbers, Social Security numbers, credit card numbers, and so on–all of which most of us would reasonably view as private and confidential.
That brings us to New York state, where federal prosecutors have been arguing that no wiretap order is necessary. They insist that touch tones cannot be “content,” a term of art that triggers legal protections under the Fourth Amendment.