I am wondering this as well. I found one that worked on my LG Spectrum and things were flawless. Personal Call & Voice Recorder, the free version to boot. It was running well on my Spectrum with Android version 2.0.4 I believe I had. I had upgraded to ICS (4.0.4) and it did not work anymore! I went through about 50 different apps, testing them out over like 3-4 days. Finally found one that worked. Manage Your Calls Free. It was working extremely well, voice quality was amazing! I accidentely uninstalled it and then put it back on. For some reason, it didn't work anymore. If anyone knows of an app out there...PLEASE HELP!!!
Problem is now solved with me!!! I have an LG Spectrum running ICS. 4.0.4. "Calls Recall" from eupheme is the answer!!! Amazing call quality directly from the line and not the mic! Hope it works for you as well!