At least in two cases, we may need to record the incoming/outgoing calls on a mobile phone automatically: 1) take evidence; 2) reserve for memo (to memorize the important or meaningful content inside, such as phone number, street address, some sweet memories or tender words from your lover). However, even the latest version of Android OS does not provide such a practical built-in function (I guess that may be for security and privacy concerns). Fortunately, there are many 3rd-party such applications, and callX is one of the best that AppNee wants to share with you (Automatic Call Recorder is another one).