I believe that the laws on recording phone calls vary by state. I used to work for the state of Iowa and our legal department explained it that in Iowa, you could record a call as long as one party consents to being recorded.
Here is something I found on it.
The U.S. federal law allows recording of phone calls and other electronic communications with the consent of at least one party to the call. A majority of the states and territories have adopted wiretapping statutes based on the federal law, although most have also extended the law to cover in-person conversations. 38 states and the D.C. permit recording telephone conversations to which they are a party without informing the other parties that they are doing so.
12 states require, under most circumstances, the consent of all parties to a conversation. Those jurisdictions are California, Connecticut, Florida, Illinois, Maryland, Massachusetts, Michigan, Montana, Nevada, New Hampshire, Pennsylvania and Washington.
It is illegal under all jurisdictions to record calls in which one is not a party.