C-Rec is a light application that records all calls to the SD card.
By default, recording will use the built-in microphone,
as many handsets do not provide facilities for high-quality recording directly from the GSM (google issue 2117).
As a result, quality varies with the handset model (for important calls you can turn on the speakerphone not
to miss the other party voice).
Still, in preferences you might untick Mic recording, and C-rec will try to high-quality record a call directly from GSM.
If it works this way I would appreciate you drop me an email specifying your handset brand and model.
To save sd card space you can filter and exclude recordings based on inbound/outbound calls or whether it is a (un)selected contact.