How to record incoming/outgoing calls in nokia lumia 520? Even 3rd party apps not supporting this feature.
You can't record a call on Windows Phone devices. Neither built-in, nor third-party. Note that recording a telephone call is illegal in many places.
It is currently not possible with third party apps, but it could be possible with a third party app using the VoIP APIs. Once voice data is routed through another endpoint, like Twilio, they could do whatever they wanted with the voice stream including recording it.
While the other answer includes it maybe illegal in some instances, it may be a legal requirement in another, like call center recording or other business functions.