In order to answer this question, we have to look at the FCC Rules and state law.
According to §73.1206 of the FCC Rules (which does also apply to LPFM stations), the station must get the other party's consent to record a conversation for broadcast or broadcast the conversation live over the air unless it is obvious that the conversation will be broadcast, such as in a call-in show.
What you can't do is originate a live call over the air. If you want to call out to someone and put them on the air, you need to call them first while off the air, get their permission to be on the air and then bring them up on the air. Some stations have received fines for "dialing out on the air" without the other party knowing that when they answer the phone, they are already on the air. Other stations have received fines for recording prank calls and then broadcasting them without the called party's consent.
In addition, the following states require that both parties have given consent to be recorded, regardless of whether the call will be broadcast or not:
- California
- Connecticut
- Delaware
- Florida
- Illinois
- Maryland
- Massachusetts
- Michigan
- Montana
- Nevada
- New Hampshire
- Oregon
- Pennsylvania
- Vermont
- Washington
