In Australia, it is against the law to record a private
conversation without the consent of the other person.
The Telecommunications
Interception and Access Act 1979 makes it an offence to
listen to a live phone call or call recording without the
permission of one or both of the parties involved.
It does not matter how you record the conversation.
This includes tapping a phone line, using an app to record phone
calls on a mobile phone, or using a call recorder device.
Depending on the specific jurisdiction, there are exceptions to
this general rule. There are also different pieces of legislation
that apply in different states and territories.
However, generally speaking, if you covertly use a listening
device (such as a mobile phone) and publish or distribute that
material, you can be committing a criminal offence.