A base station may include a transceiver, an indicator, and a processor programmed to detect presence of a key fob using one or more inputs. When the key fob is detected, the processor may direct the transceiver to broadcast an interference signal using the transceiver to prevent the key fob from detecting and responding to challenge requests and set the indicator to indicate presence of the broadcast. When an access request is received from a modem, using the transceiver the base station may temporarily discontinue broadcast of an interference signal to send a challenge request to the key fob and receive a challenge response, and send a response to the access request including information based on the challenge response.