How to record phone calls on my iPhone 5?

I know this is illegal in some states, I need to record my any phone call my husband makes. I would like it to be transparent or a secret so he doesn't know it's recording. Like an app or something, maybe something cheap or free? The reason I need to do this is because he never talks to his parents in front of me and I need a way to record his phone calls without him knowing and to be able to listen to the full phone call. I want to spy on my husband. This issue is complicated so please, save the sarcastic answers and please help me. I really need it.

I don't know any apps but if you go to voice recorder you can hide it in the room he goes in and it will record the conversation

The app named "Secret Voice - Recording Voice Secretly" would help you in this. Just install the app from https://itunes.apple.com/...0488?mt=8… Hope it's all that you want.