A near field communication (NFC) router of a mobile device receives a first message from an external NFC device and, in accordance with a first active rule, processes the first message as being targeted to a first host processing device of the mobile device. When the NFC router receives a second message from the external NFC device and detects a bit pattern in the second message indicating that the first host processing device is not an intended target of the second message, the NFC router activates a second rule. When the NFC router receives a further first message from the external NFC device, the NFC router processes the further first message as being targeted to a target host processing device in accordance with the second active rule.