The modern ip radio gateway and telephone interface is typically a base station controller. These hardware solutions are reliable and intelligent, and they provide an agnostic interface for all major UHF, VHF and digital radio based stations. In addition, communication between the radio over IP gateway and the communication network’s interfaces can be IP/SIP, 4W E/M and 2-W analog.
The most common IP radio gateway uses radio over a SIP/VoIP network. VoIP, which stands for voice over Internet protocol, is a family of technologies used to transport voice-based communications over IP-based networks. RoIP, which stands for radio over Internet protocol, is a member of that family; it is responsible specifically for transporting two-way communication, essentially VoIP with Push to Talk (PTT) capabilities.
Most gateways also support radio over legacy networks using analog or 4W circuits. Such a unit combines the functions of a base station controller with the functions of a radiotelephony interface. Usually, the unit will support the migration from older systems using a dual-circuit interface. Also, it can operate in both SF and 4W E&M signaling mode, and it uses a legacy decoder to resolve PTT.
These systems allow multiple users to connect to a single radio circuit at the same time. Entry-level systems may only be able to support several users, while sophisticated systems can support much more. All connected users can list to traffic reception and transmission. Only one user, however, can speak at a time. If multiple users access the PTT, the system will use a PTT priority management system.
The most significant aspect of modern radio interoperability solutions is bandwidth usage. The optimal technique will use the theoretical minimum bandwidth. Some inefficiency is acceptable with smaller networks depending on the cost of the bandwidth. However, small inefficiencies become significant when the system is facilitating a large number of multicast audio streams.