The Bush Administration has carefully described its warrantless wiretapping program by saying it involved international phone calls and emails where at least one party was suspected of ties to terrorist groups and one party was inside the country. Most, including this reporter, have assumed that this meant that the program eavesdropped on the communications of Americans who emailed or called a suspected terrorist outside the country.
http://blog.wired.com/27bstroke6/2007/09/us-warrantless-.htmlAlso see:

US Justice Dept.’s warrantless eavesdropping rejected

The U.S. Department of Justice asserts it doesn’t need to obtain a wiretap court order to listen to which touch tones are pressed when people are on the phone.
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At issue in this case is not whether the FBI can legally eavesdrop on a telephone conversation between two Americans. It can–if it obtains a wiretap order from a judge.But the Justice Department considers that too limiting. This is why federal prosecutors asked a judge for permission to record post-cut-through dialed digits (PCTDDs) without having to prove they have probable cause, meaning actual evidence of criminal activity. Instead, prosecutors say, all they should need to claim is that the PCTDD information is somehow “relevant” to a criminal investigation.
http://news.zdnet.com/2100-1035_22-6210080.html