is this legal to record a conversation?

Unfortunately, it is not always easy to tell which law applies to a communication, especially a phone call. For example, if you and the person you are recording are in different states, then it is difficult to say in advance whether federal or state law applies, and if state law applies which of the two (or more) relevant state laws will control the situation. Therefore, if you record a phone call with participants in more than one state, it is best to play it safe and get the consent of all parties. However, when you and the person you are recording are both located in the same state, then you can rely with greater certainty on the law of that state. In some states, this will mean that you can record with the consent of one party to the communication. In others, you will still need to get everyone's consent.

Known as the "Two-party Consent" law...the following states require both parties consent:

California, Connecticut, Florida, Illinois, Maryland, Massachusetts, Montana, Nevada, New Hampshire, Pennsylvania and Washington.

Although they are referred to as "two-party consent" laws, consent must be obtained from every party to a phone call or conversation if it involves more than two people.

One person answering your question included the State of Alabama. As an officer in Alabama I am aware that the State of Alabama is NOT a two-party consent state. Additionally, your state, Missouri, is also NOT a two-party consent state.

In Missouri, a conversation can be recorded as long as 1 party gives permission.

If you want to record your own telephone conversations, you can do so without notifying the other party.

You can not record your wife's, or children's phone calls without permission of 1 party in the conversation.

Reporters Committee for the freedom of the press;

An individual who is a party to a wire communication, or who has the consent of one of the parties to the communication, can lawfully record it or disclose its contents, unless the person is intercepting the communication for the purpose of committing a criminal or tortious act. Mo. Rev. Stat. § 542.402. Recording or disclosing the contents of a wire communication by all other persons is a felony.

Anyone whose communications have been recorded or disclosed in violation of the law can bring a civil suit to recover the greater of actual damages, $100 a day for each day of violation or $1,000, and can recover punitive damages, attorney fees and litigation costs as well. Mo. Rev. Stat. § 542.418.

A Missouri appellate court has held that radio broadcasts from cordless telephones are not wire communications, and thus, recording such radio broadcasts is not illegal under the eavesdropping statute. Missouri v. King, 873 S.W.2d 905 (Mo. App. 1994).

It is also a felony to view or photograph a person in “a state of full or partial nudity” if the person “is in a place where he would have a reasonable expectation of privacy.” Mo. Rev. Stat. § 565.253.

No. Your state is on the list of states that require you to notify the other party that they're being recorded:

Alabama

Alaska

Arizona

Arkansas

Colorado

District Of Columbia

Georgia

Hawaii

Idaho

Illinois

Indiana

Iowa

Kansas

Kentucky Louisiana

Maine

Minnesota

Mississippi

Missouri

Nebraska

Nevada

New Jersey

New Mexico

New York

North Carolina

North Dakota

Oklahoma Oregon

Ohio

Rhode Island

South Carolina

South Dakota

Tennessee

Texas

Utah

Vermont

Virginia

West Virginia

Wisconsin

In some cases, no.