MOST PHONES DOES NOT SUPPORT CALL RECORDING. Blame Google or your phone manufacturer not me!
If it fails with high quality sound recording (voice line) this app will switch back to the MIC recording, no ads, open-source, GPLv3.
Google knows about issue but do nothing, can read more here:
Market link: com.github.axet.callrecorder
Web site: https://gitlab.com/axet/android-call-recorder
Market downloads: 500-1,000
Market rating: 3.5 / 5.0