Is it legal to record incoming &/or outgoing telephone conversations in your home &/or business without the other person's knowledge; and then also is it admissable in a court of law?
Florida's wiretapping law is a "two-party consent" law. Florida makes it a crime to intercept or record a "wire, oral, or electronic communication" in Florida, unless all parties to the communication consent. See Fla. Stat. ch. 934.03.
Florida law makes an exception for in-person communications when the parties do not have a reasonable expectation of privacy in the conversation, such as when they are engaged in conversation in a public place where they might reasonably be overheard.
If you are operating in Florida, you may record these kinds of in-person conversations without breaking the law.
However, you should always get the consent of all parties before recording any telephone conversation and any in-person communication that common sense tells you is private.
In addition to subjecting you to criminal prosecution, violating the Florida wiretapping law can expose you to a civil lawsuit for damages by any injured or aggrieved party.