Some Android phones have following issues:
- Can't record calls.
- Can record calls, but in recordings the sound of your side is very weak.
- Can record calls, but in recordings the sound of the other side is very weak.
- Can record calls, but during recording you can't hear the caller's voice.
- Can record calls, but during recording the caller can't hear your voice.
- Can record calls, but when you play back the recordings they sound like fast forwarding or fast rewinding.
- Some other issues maybe.
These issues are not caused by the call recorder, actually they are caused by the manufacturer intentionally - the manufacturer disabled the call recording feature of your phone. You should install a powerful call recorder that can fix this problem, for example this Call Recorder.
About bluetooth call recording problem
Some phones support bluetooth call recording perfectly, just install any call recorder and go.
The hardware of some phones don't support bluetooth call recording, for example Galaxy Note 2 GT-I7100, GT-7105, Galaxy S3 GT-I9300 etc that use the WM1811 audio chip. In this case all call recorders don't work.
The hardware of some phones support bluetooth call recording but the ROM doesn't support it, for example Galaxy Note3, Galaxy Note4, Galaxy S2, Galaxy S5 etc. In this case you should root your phone and install a call recorder that can fix this problem, for example Boldbeast Call Recorder, it can fix this problem for many phones.
Please note Galaxy phones have many variants, they are different from each other, for example Galaxy S3 GT-I9300 doesn't support bluetooth call recording, but Galaxy S3 SGH-I747, SCH-I535 may support it, or can be fixed.
How manufacturers disable the call recording feature
Indeed almost all android phones' kernel support call recording perfectly, manufacturers usually disable the call recording feature out of the kernel (not in the kernel). If the recorder gets root access and it supports your phone it can fix the recording problem, no need to change the kernel.