Abstract: The system includes a first data channel established between the mobile communication unit and a wireless communication system. The first data channel is configured to receive the data communication. A second data channel is established between the wireless communication system and another communication system. The second data channel is configured to receive the data communication. An interworking unit is responsive to the first data channel and the second data channel. The interworking unit receives the data communication from the second data channel and queues the data communication when the first data channel cannot receive the data communication.

Abstract: The method includes establishing a first data channel (16) between the calling communication unit (44) and the wireless communication system (40), the first data channel configured to receive and transmit the data communication (21); after establishing the first data channel and before a second data channel (22) has been established between the wireless communication system and the called communication unit (84), receiving by the calling communication unit a message (19), the message indicating that the second data channel has been established; and based on the message, the calling unit transmitting the data communication via the first data channel.

Abstract: A radio (100) transmits and receives encrypted signals having unencrypted key identifiers, allowing other radios having the corresponding key identifiers and encryption keys to communicate with radio (100). Prior to transmitting an encrypted message, radio (100) selects a unique key identifier automatically and uses the corresponding encryption key to encrypt the message that will be transmitted. Radio (100) transmits the key identifier in an unencrypted format with the encrypted message in order to allow other radios to determine the encryption key used in encrypting the message. When receiving an encrypted message, radio (100) uses the predetermined process stored in the radio (100) to properly select the proper encryption key for use in decrypting the incoming message.

Abstract: A radio (100) capable of automatically selecting an encryption algorithm from among a plurality of algorithms (122 and 124) is disclosed. The method for automatically selecting the proper encryption hybrid includes the steps of: attempting to decrypt the encrypted signal with one of the plurality of encryption algorithms; determining if the encryption algorithm used to decrypt the encrypted signal matches the encryption algorithm used by the encrypted signal; and developing a control signal upon the proper matching of the encryption algorithms.

Abstract: A trunked communication system (400) transmits and receives encrypted signals over the system control channel (402). The trunked system (b 400) includes a plurality of radios (300) which can communicate with the communication system via control channel (402). By using control information signals and system information signals radios (300) can determine if it they are capable of decrypting the encrypted control information signals sent over the control channel (402). This is done by first determining if the encryption identification field found in the unencrypted system information signal matches an encryption identification field found in radio (300). If a match is found between the radio's encryption identification and the encryption identification field in the system identification signal radio (300) loads the encryption into the encryption circuitry in order to successfully decrypt the control information signals.