Check how to record a phone call on an iPhone, you need to use an app since iPhones don't have a built-in feature for this. One easy app is "Rev Call Recorder" to record all the call within your iPhone device. Here are the steps below on how to use it:

1. Download the "Rev Call Recorder" app from the App Store.
2. Open the app and sign up.
3. When you want to record a call, open the app and press "Record."
4. The app will dial a number, and then you can add the person you want to call.
5. After the call, the app will save the recording automatically for you.