3.1.4.2 Cancellation
The higher layer can cancel the pairing attempt at any time. When the client is in the CONNECTING, WAITING_FOR_SERVER_READY, WAITING_FOR_PAIRING, WAITING_FOR_CHALLENGE_REQUEST, or WAITING_FOR_CHALLENGE_RESPONSE state, the client initiates a disconnect of the control channel, stops the ClientGuardTimer (section 3.1.2), and transitions to the FATAL_ERROR state. When the client is in any other state, the client MUST ignore the request.