This program records phone calls from the phone line on some phones. Such recording is not usually available out-of-the-box, it needs hardware support in your OS kernel and root access. If your device has no such support, the program still records phone calls, but you need to select Android API
in settings->recording and the recording will most likely proceed from the microphone, not from the line.
For more information please read thread on xda-developers.com - http://forum.xda-developers.com/showthread.php?t=1441643