Transom Tool: Recording Phone Calls

Transom Tool: Recording Phone Calls: "The first thing to consider about recording phone calls it to make sure that what you’re doing is legal. Laws vary widely from place to place, with dramatic differences even between states in the U.S. The safest policy is to always be upfront about the fact that you’re recording, and to get clear consent from the person being recorded."
Having said all that - this article covers several helpful techniques.