Call Recorder

Call Recorder is intended for automatic call recording from the phone line where supported by hardware and kernel. Call recording is a very device specific feature, because manufacturers often don’t implement the required functionality on the system level as they have to.
So root is a must on many devices to record phone calls from the phone line where manufacturers didn’t implement the required functionality. But it doesn’t mean the root is a savior for any device as call recording can be broken on the hardware level. Root helps often, but not always.
The app has different recording methods. If you’re lucky enough, the app won't fail to record both sides over Standard API recording method without root.