A process carried out by a first mobile radio for joining a sub-talkgroup of a first talkgroup includes receiving, via a provisioning process or via an infrastructure wireless communication interface from an infrastructure radio access network (RAN) while within wireless communication range of the RAN, a talkgroup-specific security token associated with and shared by all group mobile radios in a first talkgroup to which the first mobile radio is subscribed via the RAN. The first mobile radio then detects, via a short-range wireless communication interface, a second mobile radio, and authenticates, the second mobile radio using the talkgroup-specific security token. If the authentication is successful, the first mobile radio adds an identity of the second mobile radio to a sub-talkgroup set of mobile radios of the first talkgroup.

A mobile communication unit performs communication using a first communication scheme. A business wireless communication unit performs communication using a second communication scheme. A storage unit stores first information and second information, mapping the first information and the second information to each other, the first information being defined to receive, using the first communication scheme, service from a further communication terminal device capable of communication using the first communication scheme and the second communication scheme, and the second information being defied to perform communication with the further communication terminal device using the second communication scheme. A business wireless processing unit causes communication based on the second information stored in the storage unit to be performed preferentially, when the business wireless communication unit performs communication with the further communication terminal device while the mobile communication unit is receiving the service from the further communication terminal device.

Disclosed is a method in which a terminal provides a Mission Critical Push To Talk (MCPTT) service. The method includes receiving a group call announcement message by the terminal, which is any one of a plurality of terminals participating in a group call that is set based on the MCPTT service, comparing information regarding a first group call stored in the terminal with information regarding a second group call included in the received group call announcement message, and merging the first group call, in which the terminal is participating, and the second group call, based on a result of the comparison.

A server receives a call request for a mission critical, push to talk (MCPTT) call. In response to receiving the call request, the server accesses a mapping of an MCPTT identifier of a user equipment with an interworking identifier that is formed according to an address format implemented in Global System for Mobile communications (GSM) for Railways (GSM-R). The server then forwards the call request from the server based on the mapping. In some cases, the MCPTT identifier is a uniform resource identifier (URI) and the interworking identifier is represented in an e164 format.

A server receives a call request for a mission critical, push to talk (MCPTT) call. In response to receiving the call request, the server accesses a mapping of an MCPTT identifier of a user equipment with an interworking identifier that is formed according to an address format implemented in Global System for Mobile communications (GSM) for Railways (GSM-R). The server then forwards the call request from the server based on the mapping. In some cases, the MCPTT identifier is a uniform resource identifier (URI) and the interworking identifier is represented in an e164 format.

A system and method for multiplexing data streams in order to optimize network resources for Push-to-talk-over-Cellular (PoC) systems. One or more servers interface to the wireless communications network to perform advanced voice services for one or more mobile units therein, which include a Push-to-Talk-over-Cellular (PoC) call session. Both the servers and the mobile units that use the advanced voice services communicate with each other using control messages within the wireless communications network, and at least one of the servers switches media streams comprised of voice messages for the advanced voice services between the mobile units across the wireless communications network. At least one of the mobile units is a participant in a plurality of PoC call sessions concurrently, and at least the media streams for each of the plurality of the PoC call sessions are multiplexed into a single path.

A system and method for providing dynamic quality-of-service (QoS) for Push-to-Talk (PTT) services in a wireless communications network. One or more servers interface to the wireless communications network to perform the PTT services for mobile units therein. Both the servers and the mobile units communicate with each other using control messages transmitted across bearers in the wireless communications network, and at least one of the servers transmits media streams comprised of voice messages for the PTT services between the mobile units across the bearers in the wireless communications network. At least one of the servers sets up a dedicated bearer in the wireless communications network for at least one of the mobile units, wherein the dedicated bearer has a specified quality of service (QoS) for transmission of at least the media streams to the mobile unit. The dedicated bearer may be static or dynamic.

Methods and apparatus for initiating a PTT call from a caller client device to a recipient client device. The methods and apparatus register the caller client device with the PTT system, wherein caller data identifying the caller client device is transmitted to the PTT system; store the caller data; generate, at the caller client device, a channel request message that includes channel allocation data and call invite messaging information; transmit the channel request message to the PTT system; parse the call invite messaging information from the channel request message; generate a call invite message based upon the call invite messaging information and the stored caller data; and establish the PTT call between the caller client device and the recipient client device based upon the call invite message. Additionally, the call invite messaging information includes an identification number and not the URI of the recipient client device.

A hardened VoIP system is presented that includes secure push-to-talk voice functionality. Through the addition of encryption, authentication, user filtering, and integration with new and existing LMR systems, a secure voice platform ensures malicious software, unauthorized access and brute force security attacks will not compromise the voice communications of the system. The VoIP system is engineered to ensure graceful system degradation in the event of maintenance activities, natural disasters and failure modes. The hardened VoIP system offers the functions a LMR trunking system while utilizing broadband connections. Private calls, group calls, Emergency Alarms with covert monitoring capability, scanning and priority scanning may be incorporated into the system. The system includes a VoIP controller that serves as a trunking controller, manages available VoIP based conference bridges, and assigns them as needed to the parties involved in each voice call. The system includes multiple fallback methods that may be prioritized based on pre-failure analytics.

A hardened VoIP system is presented that includes secure push-to-talk voice functionality. Through the addition of encryption, authentication, user filtering, and integration with new and existing LMR systems, a secure voice platform ensures malicious software, unauthorized access and brute force security attacks will not compromise the voice communications of the system. The VoIP system is engineered to ensure graceful system degradation in the event of maintenance activities, natural disasters and failure modes. The hardened VoIP system offers the functions a LMR trunking system while utilizing broadband connections. Private calls, group calls, Emergency Alarms with covert monitoring capability, scanning and priority scanning may be incorporated into the system. The system includes a VoIP controller that serves as a trunking controller, manages available VoIP based conference bridges, and assigns them as needed to the parties involved in each voice call. The system includes multiple fallback methods that may be prioritized based on pre-failure analytics.