Federal Law permits the recording of a phone call with the consent of at least one party. However, federal law is not necessarily controlling in most situations. Federal law may apply, but not always, when the parties are in two different states.
The majority of states follow the federal line of reasoning and permit single party consent to tape a call. Thus you don't have to get the other person to agree. States which are believed to follow this rule include:
District Of Columbia
A minority of states require both parties to consent to the recording of a phone call. If a person tapes in these states without two party consent, there can be both civil and criminal consequences. Those states are believed to be:
Montana New Hampshire
Taping to Submit as Evidence in Court
Even if only one party consent is required in a state, it is at the Judge's discretion whether a tape or transcript can be admitted into evidence.
Some Interesting Exceptions
In some states a limited exception is made for taping by businesses under certain circumstances. In California there are severe penalties, monetary fines and jail, for taping without consent but consent may also be implied and if a characteristic "beeping" warning is used, no consent is required. Indian Reservations and Military Bases fall under the federal rule even if they are located withion a two party consent state.
Taping phone calls without consent can be a mixed bag. Anyone contemplating taping clandestinely should seek the advice of an attorney and not rely on the above information which is offered for educational purposes only.