The gateway solution enables one device to translate a unicast (single) SIP call to a broadcast/multicast in the audio over IP domain, for purposes such as group addressing. This allows use of the same codec to distribute a multicast announcement that the receiving devices understand. The SIP gateway can also be programmed to prioritize announcements over other audio streams. The SIP protocol will translate the priority announcement request only to the targeted groups or zones, allowing the general audio over IP streaming to continue uninterrupted in all other areas.
This is the essence of what it means when comparing audio over IP and SIP concepts: a continuous stream, zoning and priority compared to temporary, exclusive connections. Integrating both over a common network infrastructure creates a solution that provides the best of both worlds.