This is the phone i have, It came with a headset which allows you to use any headphones you wish.
Step 1: What You Need...
A mobile phone (Not pictured as i used phone to take pictures)
A Headset with a head phone port
A Sound card with a LINE IN port
Audio Recording software
A Headphone Cross over cable
Step 2: Connect It Up
Step 3: Load Up the Software
Step 4: Record
Step 5: Make a Call
Make a call, When it begins to ring hit record, talk away with the mouth peice, Once phone call is done stop recording
Step 6: Save and Edit Your Audio
(PS this is my first instructable please comment with advice and improvements)