Abstract: A radio is authenticated at the site and unique authentication information for the radio is stored at the site. A subsequent non-authentication message from the radio is received at the site and authentication information in the non-authentication message is identified. The unique authentication information stored at the site is compared with authentication information identified in the non-authentication message. If there is a match, the non-authentication message is authenticated with an authentication code included in the non-authentication message, wherein a predefined portion of the authentication code is obtained from at least one of a header portion or a data portion of the non-authentication message. Upon successfully completing authentication, the site repeats the non-authentication message towards destination radios indicated in non-authentication message.

Abstract: A method for operating with KMFs includes a communication device having a memory device: receiving a designation of a primary KMF for the communication device, wherein only one primary KMF is designated for the communication device at any given time instance; receiving a designation of a secondary KMF for the communication device; storing, within the memory device, a first and a second set of crypto groups, wherein each crypto group within each set of crypto groups comprises at least one keyset, wherein each set of crypto groups is associated, within the memory device, to only one KMF identifier; associating, within the memory device, the first set of crypto groups to an identifier for the primary KMF; and associating, within the memory device, the second set of crypto groups to an identifier for the secondary KMF.

Abstract: A method for selecting a channel for group communications in a conventional multi-channel communication system comprises receiving, for a plurality of channels in the multi-channel communication system, a talkgroup assignment list for the channels that identifies a set of talkgroups assigned to use the corresponding channels. A subscriber unit receives talkgroup assignment lists for multiple different channels, determines a desired talkgroup, and selects a channel assigned to the desired talkgroup using the received talkgroup assignment. The talkgroup assignment list is developed for at least one channel in the multi-channel communication system and identifies a set of talkgroups assigned to use the corresponding channel. The list is transmitted for the channel to a subscriber unit and is used by the subscriber unit to register with the system and affiliate with a talkgroup supported by the channel in the conventional multi-channel communication system.

Abstract: A radio is authenticated at the site and unique authentication information for the radio is stored at the site. A subsequent non-authentication message from the radio is received at the site and authentication information in the non-authentication message is identified. The unique authentication information stored at the site is compared with authentication information identified in the non-authentication message. If there is a match, the non-authentication message is authenticated with an authentication code included in the non-authentication message, wherein a predefined portion of the authentication code is obtained from at least one of a header portion or a data portion of the non-authentication message. Upon successfully completing authentication, the site repeats the non-authentication message towards destination radios indicated in non-authentication message.

Abstract: A method for operating with KMFs includes a communication device having a memory device: receiving a designation of a primary KMF for the communication device, wherein only one primary KMF is designated for the communication device at any given time instance; receiving a designation of a secondary KMF for the communication device; storing, within the memory device, a first and a second set of crypto groups, wherein each crypto group within each set of crypto groups comprises at least one keyset, wherein each set of crypto groups is associated, within the memory device, to only one KMF identifier; associating, within the memory device, the first set of crypto groups to an identifier for the primary KMF; and associating, within the memory device, the second set of crypto groups to an identifier for the secondary KMF.

Abstract: A method for indicating the status of communication channels assigned to a talkgroup includes: determining the channels in various sites in a conventional communication system that service a talkgroup for media transmissions between subscribers of the talkgroup; receiving notification of the status of transmission activity on the channels; and based on the notification, providing an indication of the status of the channels assigned to the talkgroup so that the talkgroup or subscribers of the talkgroup can choose to proceed with a talkgroup communication. The notification may be received by an infrastructure device in an RF site or a central controlling entity. The indication may be that the channel is free for transmissions or is busy.

Abstract: A security gateway and an initiating device perform methods for establishing a security session. The methods includes the security gateway: receiving a first message from an initiating device, the first message including a first message authentication code; validating the first message using the message authentication code; and responsive to the validating, sending a second message to the initiating device, the second message including a timestamp and further including a second message authentication code for authenticating of the timestamp by the initiating device, wherein the first and second messages are used to establish the security session, and the authenticated timestamp is used for subsequent replay protection of messages between the security gateway and the initiating device. The method further includes the security gateway validating a dynamically assigned IP address for the initiating device to use in authorizing VPN traffic between the two devices.

Abstract: Disclosed is a method for encrypted communications. A first IPsec endpoint selects a security association (SA) from a security association database (SAD) by using a selector and then extracts an indexing parameter from SA. The indexing parameter is used to determine an active key location from a key storage database (KSD). Data packets are then encrypted using a key from the active key location. The first IPsec endpoint also forms a security parameter index (SPI) in a header of the data packet by using a keyID from the active key location and transmits the encrypted data packet with the header indicating the SPI to a second IPsec endpoint.

Abstract: A method for indicating the status of communication channels assigned to a talkgroup includes: determining the channels in various sites in a conventional communication system that service a talkgroup for media transmissions between subscribers of the talkgroup; receiving notification of the status of transmission activity on the channels; and based on the notification, providing an indication of the status of the channels assigned to the talkgroup so that the talkgroup or subscribers of the talkgroup can choose to proceed with a talkgroup communication. The notification may be received by an infrastructure device in an RF site or a central controlling entity. The indication may be that the channel is free for transmissions or is busy.

Abstract: A method for selecting a channel for group communications in a conventional multi-channel communication system comprises receiving, for a plurality of channels in the multi-channel communication system, a talkgroup assignment list for the channels that identifies a set of talkgroups assigned to use the corresponding channels. A subscriber unit receives talkgroup assignment lists for multiple different channels, determines a desired talkgroup, and selects a channel assigned to the desired talkgroup using the received talkgroup assignment. The talkgroup assignment list is developed for at least one channel in the multi-channel communication system and identifies a set of talkgroups assigned to use the corresponding channel. The list is transmitted for the channel to a subscriber unit and is used by the subscriber unit to register with the system and affiliate with a talkgroup supported by the channel in the conventional multi-channel communication system.

Abstract: A method for managing a packet in a communication system between two or more endpoints, a sender and one or more recipients, comprises receiving a first packet comprising a source identifier that uniquely identifies a sender of the first packet and a current source time assigned to the first packet by the sender, determining a received time for the first packet, retrieving a cached source time assigned by the sender to a second packet that was received prior to receiving the first packet, and determining whether to discard or process the first packet based on the current source time, the received time, and the cached source time. The current source time, the received time, and the cached time, in addition to predetermined parameters such as a maximum age and an anti-replay window allows a recipient to determine whether to process or discard a packet.