The reason they keep focusing on phone calls is because there is a fairly substantial body of law that protects phone communications from government wiretapping (in response to the way J. Edgar Hoover conducted his activities). Internet and electronic privacy is a fairly new branch of law, and they are still trying to figure out ways to legislate it in Congress and in the courts . In the meantime, since phone calls already have such robust protection, it's the easiest thing to go after a the moment.
This is likely why Obama was so adamant that our phone calls weren't being tapped, he knows the legal implications of admitting that they were.
"WASHINGTON (AP) — In a heated confrontation over domestic spying, members of Congress said Wednesday they never intended to allow the National Security Agency to build a database of every phone call in America. And they threatened to curtail the government's surveillance authority."
After suffering with cancer for quite sometime, one of the greatest and most influential writers of our time has left us. Each book he has ever written occupies a very special shelf in my library, from Cyprus to his final publication of Essays. Whether you agreed with him or not, and a few rare times I did not, he was a brilliant thinker, writer and orator. For a time, the world will be a slightly darker place with him gone.