If I call a company that says they are recording the call, is it legal for me to record the call as well? How?

You did not identify what State. In Georgia, it is always completely legal to record any conversation, including telephone, so long as you have the consent of any one party to the conversation. If you are also on the call, you may record, since you are a participant that consents. I know this sounds strange, but it is the law in Georgia. I have won a bet on this more than 5 or 6 times, and have even won on this very argument in Georgia courts. If you are in another state, the law is likely different. If so, you should resubmit your question, and identify what state. It varies from state to state.