This question comes up frequently in divorce and custody cases, and the answer is: it depends.
Both Federal and state laws apply to secret recordings, and there can be both civil and criminal penalties for violations.
Federal law allows you to secretly record your phone conversation as long as one party consents – and since you’re on the call, you certainly “consent” to your own secret recording. Federal law is called a “one-party consent” law.
The key question is what does your state law allow: does it allow you to record with the consent of just one party (you), or do all parties to the conversation have to consent?
Arizona is a “one-party consent” state, but these other states are “two-party consent” jurisdictions: California, Connecticut, Florida, Illinois, Maryland, Massachusetts, Montana, New Hampshire, Pennsylvania and Washington.
You need to follow the law in the more restrictive state. This means if you’re in Arizona but are calling someone in California, you should not secretly record their phone call without their consent, because California law doesn’t allow it, even though Arizona does. And if you’re in California or one of the other two-party consent states, forget it.
Even if the recording isn’t illegal, that doesn’t mean a Judge will necessarily view secret recordings favorably. Absent some compelling reason (e.g. to have proof of verbal abuse, threats or criminal activity), a Judge may very well question the character of a person who secretly records all their conversations with their former spouse or partner.
Before recording, it’s best to get legal counsel to protect yourself and discuss ways to get the evidence you need in a manner that can be used in court and makes you look good.