Call recording facility on smartphone is a very useful feature in many circumstances and I think it is pointless to mention its uses here. Some Android phones are available with built-in call recorder feature in certain regions and if your device missing this feature, there is plenty of third-party app available on play store in both free and premium features.
If you own a Sony Xperia V phone and if it is running on Android Jelly Bean, you can enable built-in call-recording feature on it. The method discovered by the XDA forum member Nicemblem works probably on other Sony Xperia devices as well, including Xperia Z.
Before going to the subject, keep in mind that, recording your own phone calls may not be legal in your country. If it is legal in your country, just follow below guide.
Download the “CallRecordEnable….” zip file from source link given below and copy it to your device’s SD card. Boot your device into recovery mode and flash the zip file from recovery. Then reboot your device.
[To boot Xperia V into recovery mode, turn off it, press and hold Vol Up +Vol Down + Power buttons together]
To record a call, just press menu during a phone call. You will find a new “turn on recording” option. Your recording will be saved in sdcard/record, after you stop the call or hang the phone. [Source- XDA]