Habeas Corpus was not dispensed with! To do so would require an Amendment.

What is the evidence that all phone calls were intercepted? Just look at the feasibility of doing that. There are 330 million people in the country. For discussion let us postulate that half of them have phones. I know my phone usage is below average, but using that will give an understanding of the magnitude of the difficulty of what you believe. That below average phone usage gives us 710 million hours of phone calls per month.
I know you will suggest that computers are used to scan for stuff but that does not fit with your original premise, but even so. Such a progrom, assume the most efficient, can not leave you with less than 10% or 71 million hours PER MONTH. The manpower does not exist to deal with that kind of input. Even using all of our military assets it would take a month and a half to go over that much material.