One illustrative method involves the steps of receiving a ciphering mode information message from a wireless network; identifying and processing valid radio bearer downlink ciphering activation time information in the ciphering mode information message when it is part of a security mode command message; and refraining from processing any valid radio bearer downlink ciphering activation time information in the ciphering mode information message when it is part of a message that is different from the security mode command message (i.e. when it is part of a radio network subsystem relocation procedure). The method may include the additional steps of producing valid radio bearer uplink ciphering activation time information for inclusion within a response message when the ciphering mode information message is part of the security mode command message; refraining from producing any valid radio bearer uplink ciphering activation time information when the ciphering mode information message is part of a message that is different from the security mode command message; and causing the response message to be sent to the wireless network.