An empty recording does not always mean the call cannot be recorded. There are two different cases: calls made inside apps, and carrier calls using VoLTE or Wi-Fi Calling.

Calls made inside Skype, WhatsApp, Viber, Telegram, Messenger, and similar apps are not supported. On most phones, their audio never reaches the telephony path that Android allows an app to record.

On some phones, these calls are recorded anyway. This happens when the phone reports an app call in the same way as a normal call. There is no setting to enable this, and there is no list of phones where it works. These recordings are not supported or tested. They may stop working after any system or app update, and Call Recorder cannot fix this. If it works on your phone, you can use it, but do not rely on it.

VoLTE and Wi-Fi Calling are different. They are normal carrier calls made through the SIM card. On most devices, Call Recorder records them like any other call. On some devices, however, the recording is empty or silent. This happens most often with Wi-Fi Calling on Samsung phones, both with Exynos and Snapdragon chips.

To check whether Wi-Fi Calling is the cause, turn it off in your phone settings. This option is usually under call or connection settings. Then make a test call. Call Recorder marks Wi-Fi Calling recordings with "[wifi]" in the recording note.

If calls inside apps create empty files or cause recording problems, turn on "Ignore VoIP calls" in Settings > Recording > Standard API > Other. This setting is off by default. When it is on, Call Recorder does not start recording automatically for a call detected as VoIP.

For help with other recording problems, see Settings for call recording.