Is it illegal to record someone over the phone without their knowledge in Oklahoma? I've been told it varies state to state.

The safer path is to assume you are being recorded and be appropriate, proper, and within the law when you speak to anyone . The law with regard to the admissibility of telephone calls varies by state. I cannot speak to the illegality of these issues as I do not know the answer.

You might go to: http://www.rcfp.org/reporters-recording-guide/state-state-guide I can NOT guarantee you the accuracy of what is contained therein. However, it should give you a good start. The previous advice given to you was excellent. I would also suggest you speak with your attorney and tell him about this situation.

Yes, as long as both participants are in Oklahoma, you can record your own conversations without telling the other party. However, if one of the participants to the call was in another state, you would also have to consider that state's phone recording laws. The majority of the states allow their citizens to record their own conversations without telling the other party.