A free program for Android, by Ayago Dev.

Automatic Call Recorder: Voice Recorder Caller ID is a free voice recording app that lets you record both incoming and outgoing calls on your Android smartphone. You can use it to save your important conversations or listen to them later. It allows you to record meetings, personal notes, classes, songs, and much more. You can even set the source (mic, voice call, a video camera) and automatically choose the best recording strategy for your device.

Automatic Call Recorder – ACR is a powerful recording tool that will help you save your best moments. It’s a completely free app, so you don’t have to worry about any fees.